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Breeding Systems and Rarity in New Zealand Myosotis 
A thesis presented in partial fulfilment of the 
requirements for the degree of 
Doctor of Philosophy 
In 
Ecology 
at Massey University, Palmerston North 
New Zealand. 
Andrea Mary Brandon 
2001 
Abstract 
Rarity in N ew Zealand Myosotis was explored at several different levels for this thesis . 
Within the genus, there are many rare species, encompassing several different types of 
rarity, and many of these are considered threatened in some way. In  addition, the genus 
contains species that exhibit a wide array of floral forms, each of which can be  associated 
with a distinct form of rarity. 
The reproductive biology of selected Nelson taxa was investigated in several specIes 
covering a range of floral morphologies, including the previously unstudied brush 
blossom floral syndrome. Species were found to fall into one of two mating types based 
on the d egree of herkogamyl exhibited by the flowers . Species with flowers that are 
herkogamous throughout their life, require polIinators to set seed while those that are not 
herkogamous at some stage during anther dehiscence, are self-fertile and able t o  self­
pollinate autonomously. All species studied were self-compatible. Considerable 
variation in seed production was observed under natural conditions for those species that 
required pollinators to set seed. For these pollinator-requiring species, local population 
density had strong effects on seed set, while population size had no effect. These plants 
were always pollen limited in Iow-density patches . For a self-fertile species, seed s et was 
always high and unaffected by either local density or population size and pollen was 
never limiting. These results indicate reproductive success in pollinator-requiring species 
of Myosotis is subject to Allee effects and these effects occur at a very local scale. These 
results have implications for the assessment and management of threatened Myosotis 
species in particular and rare plants generally. It is essential to know the pollination 
requirements and levels of density dependence for reproduction both for the assessment 
of threat and for determining management strategies for threatened plants. 
Self-compatible, but pollinator-requiring species are prone to autogamy and geitonogamy 
and therefore inbreeding depression. One strategy to avoid this is to increase dichogamy 
and synchronise inflorescence development. Pollination was studied in the 
geographically restricted, ultramafic endemic Myosotis monroi, a species that has a 
relatively large floral display and whose flowers often bear precocious styles prior to 
1 A glossary of technical terms follows the appendices 
11 
buds opening. In general, precocious styles are assumed to be receptive and indicate 
protogyny. Stigmas were receptive at this stage and some pollination occurs during this 
precocious phase. Stylar precocity effectively lengthens the female-only phase in this 
species. This is the first time that precocious styles have been proved to be  receptive at 
this stage. M. monroi also shows far greater phenological synchrony of within plant 
flowering than five other species of New Zealand lvfyosotis. It is thought that the impact 
of a large floral display on levels of geitonogamy in M monroi is alleviated to some 
degree by the relatively long, initial female-only phase and phenological synchrony of 
flowering stages. 
Rarity is generally considered "the precursor to extinction" (Darwin, 1 872). However, 
there are several different forms of rarity and not all rare species are threatened. I 
examined the different rarity patterns observed within New Zealand Myosotis. New 
Zealand Myosotis species are never common, all are rare in different ways and some 
species are threatened. Some species are known to occur at one locality where they may 
be  locally common, others may occur in two or more widely disjunct geographic areas, 
while others may be  widespread but never common where they occur. A comparative 
analysis was carried out to determine whether there are morphological correlates of the 
rarity patterns seen within the genus . Local abundance, population disjunctions and 
distribution patterns of 33  Myosotis taxa were compared to aspects of their 
morphologies, including traits related to mating systems, dispersal ability and life­
histories. Taxa requiring pollinators to set seed had smaller range sizes and higher local 
population densities than those that were able to self-pollinate. Apparent adaptations for 
dispersal and life-history traits were not correlated with range size. The disjunct 
distributions exhibited by some taxa within the genus were not associated with any of the 
morphological traits. My results can assist threat assessment and conservation 
management for New Zealand Myosotis. Locally dense, geographically restricted taxa 
are pollinator requiring while sparse, widespread taxa are selfing. C ases that break this 
general rule may be  used to identify taxa at risk. 
In the most recent taxonomic treatment, New Zealand Myosotis is initially split into two 
maj or clades depending the degree of anther exertion exhibited by the flowers. This has 
led to the recognition of species that cannot be distinguished in any other way. S pecies 
limits were examined in one such species complex; the vegetatively indistinguishable M 
III 
forsteri and M. venosa. S everal floral and vegetative characters were measured and 
compared. Filament length was the only significant character that could be used to 
distinguish the species, and even this was not 1 00% reliable. Filament length determines 
the degree of self-pollination that can occur and whether or not reproduction is assured. 
The continuous variation observed in filament, style and anther lengths and corolla sizes 
shows that there is a lot of phenotypic variation within each taxon. Geographic dines 
are observed in vegetative traits that are independent of mating system. This, in addition 
to the continuous variation observed in floral characters, lends some strength to the 
proposition that this species pair may be switching between the two breeding systems. 
The increased knowledge provided by the studies contained in this thesis on N ew 
Zealand Myosotis has provided a much-needed boost to our understanding of the 
population dynamics of these rare species, which ultimately can be used to guide 
conservation management for those taxa considered at risk of extinction. It can assist in 
identifYing those populations that are not threatened and it can direct efforts towards the 
more pressing problem situations . It has also highlighted the necessity for a taxonomic 
revision for the southern hemisphere section of the genus. 
Acknowledgements 
Thanks very much to my chief supervisor, Alastair Robertson, for providing the 
direction, guidance and support required that enabled me to complete this piece of 
research. Thanks also to lan Henderson for his supervision. Maps and geographic data 
used in Chapter five were produced using the mapping program "Amnesia" written in 
Visual Basic specifically for this project by Ian. 
Many thanks go to Shannel Courtney, NelsonfMarlborough Conservancy, D epartment of 
Conservation, whose knowledge, inspiration and support were vital to the realisation of 
this thesis. Simon Walls, Tim Shaw and Graeme Ure, also of DOC, provided much 
needed assistance when required, information and logistic support. 
I would like to thank Landcare Research, Lincoln, for providing access to the CHR 
herbarium, its collections and database facility. In particular, I ' d  like to thank Murray 
Parsons, Mary Korver and Debbie Redmond as they ensured the Myosotis collection 
records were entered preferentially into the database and provided me with all the 
equipment and assistance I required while gathering the data for this thesis. Also, many 
thanks to Aaron Wilton, for providing updated database versions. I would also like to 
thank David Glenny and Kerry Ford for some enlightening discussions and very 
interesting field experiences. 
I would also like to thank Pam Byrne for most excellent field assistance. Other field 
assistants who I ' d  like to thank include John Mitchell, Emily Whitehouse, Cathy Lake, 
Yvette Cottam, Krista McKinzey, Bruce Sunnex and Samson de  Jaeger. 
Thanks to Bill Malcolm for allowing me to reproduce some of his photos in this thesis 
and the DOC report. His photo of Myosotis monroi was the inspiration behind the study 
of precocious bud pollination (Chapter four) . 
I would also like to thank Sandy Robson, the Map librarian at Massey University, for all 
her assistance while gathering data for Chapter five. 
I couldn't have done it without a great deal of help from my family. In particular I'd like 
v 
to thank my mum for her much needed support along the way. Also, thanks to Auryn, 
and his wonderful uncles and aunties, and Grant. 
A very BIG thank you to Pauline and Joe, and Viv for providing wonderful hospitality to 
me while staying in Palmerston North. Also, Nomes, Don, Helen, Ron, Robyn, Eva, 
Amelia, Russ and Cindy, thanks. 
I would like to thank the Department of Conservation for funding the logistics  of this 
project, the New Zealand Vice Chancellor Committee for providing an additional 
scholarship stipend (WilIiam Georgetti Scholarship) and Massey University (doctoral 
stipend, GRF, Ecology Development Fund) . 
VI 
Table of Contents 
Abstract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  ii 
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v 
Table of C ontents . .. . . . . . . . . . . . . . . . .. . . . . . .. . . .. . . . . . .. . ... . . .. . . . . . . . ... . .. . . . ... . . . . . . . . . .. . . . . . .... . . . . . . . . . . . . .  vii 
Chapter 1 :  The biology of rarity and New Zealand Myosotis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  1 
Chapter 2 :  Mating types, herkogamy and rarity in six species of Myosotis L 
(B oraginaceae) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  22 
Chapter 3: AlIee effects in plant reproductive performance: Local density, 
population size, rarity and reproductive success in natural populations of 
Myosotis L. (Boraginaceae) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . .  43 
Chapter 4: Precocious bud pollination: Maximizing chances for cross  pollination 
in the ultramafic endemic Myosotis monroi Cheesm. (Boraginaceae) . . . . .. . . . . . 5 8  
Chapter 5 :  Rarity in NZ Myosotis L .  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 
Chapter 6: Species limits in the Myosotis/orsteri Lehm '!venosa Col. Complex . . . . .. . 88  
Chapter 7 :  Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  106 
Appendices ... . . . . . . . ... . . . .. . . . . . ... .... .... . .. .. . . . . . .. . . . .. . . . . .. . . .. . . . . . . . . . . . . . . . . . , . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .  . 
vu 
1 .  Nelson Myosotis: a report to the Conservator, Nelson-Marlborough 
D epartment of Conservation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  1 1 7 
2 .  The reproductive biology o f  Myosotis oreophila: a short report for 
Alan Mark and Katherine Dickinson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  170 
3 .  S eed set by hand-pollinated flowers of Myosotis monroi at the two 
stages, precocious buds (p) and open flowers (0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  1 77 
4 .  Pollen load on precocious and fully open flowers of  Myosotis monroi . .  1 7 8  
5 .  Specimens used for morphological measurements in the rarity in New 
Zealand Myosotis study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 79 
6 .  Specimens of Myosotis forstert and M venosa from which 
measurement data were taken . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  " . . . . . . . . .  . .  . .  1 80 
Glo ssary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  1 83 
VllI 
CHAPTER ONE 
The biology of rarity and  New Zealand Myosotis 
This chapter introduces the thesis by providing a literature review on the biology of rarity 
with particular emphasis on rare plant reproductive biology. This chapter also provides 
an overview of the systematic position of New Zealand Myosotis and summarizes work 
carried out to date on the New Zealand species in the genus. Several taxa are considered 
threatened in some way in lists compiled for conservation purposes, and there are many 
rare species. This chapter will also provide an outline of the contents of the thesis .  
The biology of rarity 
'Rarity, as geology tells us, is the precursor to extinction' 
C. Darwin ( 1 872) 
An integral part of attempting to preserve biological diversity is the conservation of 
threatened species. The premise that rare species face increased extinction risk has 
driven the assumption that rare species per se are threatened. This is certainly true in 
some cases. However, we now know from work carried out in the last couple of 
decades that there are different types of rarity, and that not all rare species face the same 
risk of extinction. The more knowledge we have about the biology of rarity the better 
we will be able to understand our rare species and make informed decisions regarding 
population management. 
Darwin wrote about rarity and its relationship to extinction, commenting that until the 
reasons for rarity were understood extinctions could not be explained (Darwin, 1872). 
Previously Lyell ( 1 830-33) had proposed a geological explanation for rarity, in  which 
rare species were old and about to go extinct. Although Darwin' s concept of rarity also 
encompassed evolution, ecology, geography and genetics, i t  was the geological theme 
that was carried forward to explain rarity well into the 20th century. This was the basis 
of Willis ' s ( 1 922) 'Age and Area' hypothesis; he thought that rare species were newly 
diverged (incipient). S ome still thought that they were old (relictual) (e.g. Fernald, 
1 9 1 8), and others (e. g. Gleason, 1 924) argued that they could be either (Fiedler and 
Ahouse, 1 992). In this respect rare species have been found to be o ld, young or of 
intermediate age (Stebbins, 1 980). However it i s  still a useful tool to use when 
considering possibilities as to why a species is rare. When looking at natural forms o f  
rarity within genera, the age o f  the taxon has been used t o  explain distributions. A recent 
study of eucalypts examined rarity from the perspective of newly diverged species and 
those of old or intermediate age (Prober, et at. 1 990). In their study Prober et al. ( 1 990) 
used phylogeny to  infer taxon age. Another method for determining age from 
cytological data has been proposed in which ploidy level was used to categorise endemic 
plants (Fiedler, 1 98 6). Fiedler ( 1 986) lists age of taxon as a factor that may be important 
in determining rarity. 
Poor competitive ability has been put forward as an explanation for rarity and could 
possibly explain the restriction of some taxa to ultramafic areas (Kruckeberg, 1 95 1 ) .  
The rare p lant, dwarf pipewort Eriocauion kornickianum, a declining species with a 
disjunct distribution, was found to have poor competitive abilities (Watson et at. 1 994). 
However, in a study of the differences between rare and common prairie grasses, sparse 
species have been found to have good competitive abilities that may offset low density 
and increase local persistence (Rabinowitz and Rapp, 1 984) . Again, there are examples 
that confirm the theory but there are also exceptions. 
Another theory was that rare species are colonisers of temporary habitats (Stebbins, 
1 980) .  However, while some rare species are confined to pioneer habitats, there are also 
a large number that are confined to climax forest habitats (Stebbins, 1 980). 
Many rare species occur on ' ecological islands' which have different environmental 
factorls, often soils of an unusual type (e.g. serpentine areas), which isolate them from 
the surrounding ' ocean' of unsuitable habitat (Stebbins, 1 980) .  Again, there certainly are 
examples of rare plants confined to these areas, but it is not a general pattern of all rare 
plants. 
Stebbins ( 1 980) called for a synthetic approach to understanding rarity, having found 
good examples for many of the hypotheses proposed. In short, there is no single factor 
that can be identified as the cause of rarity. 
2 
The meaning of rarity 
Descriptive work carried out in the first half of this century on abundances established 
the well known fact that within a community there are many rare species and a few 
common ones (Fiedler and Ahouse, 1 992) . However, most of these rare species will be 
common elsewhere within their ranges. 
The word rare has different meanings and is used to describe many different patterns of 
density and distribution. Rarity is defined simply by Gaston ( 1 994) ' as the state of 
having low abundance and/or a smaII range size ' .  Many authors have discussed the rarity 
of plants and in doing so have dealt with the concept variously (e .g . ,  Harper, 1 98 1 ;  
Rabinowitz, 1 98 1 ;  Palmer, 1 986 ;  Schoener, 1 987 ;  Fiedler and Ahouse, 1 992). These 
studies have provided insights into the biology of rarity. Plants can be rare in different 
ways and several authors have tried to define different types of rarity (e.g .  Rabinowitz, 
1 98 1 ;  Fiedler and Ahouse, 1 992) . Essentially the different forms represent particular 
range, distribution and abundance patterns within different spatial (e.g .  Rabinowitz, 
1 98 1 ; Gaston, 1 994) and temporal scales (Fiedler and Ahouse, 1 992). 
There is generally a positive correlation between size of geographic range and local 
abundance (Brown, 1 984, Gaston, 1 996, Lawton, 1 993) .  However there is a lot of 
variation such that individual taxa can be locally abundant but only have a small 
geographic range and others may be widespread but in consistently low population size 
(Rabinowitz et a!. 1 986). Rabinowitz ( 1 98 1 ) designed a method of categorizing rarity 
with a dichotomously branching system using population size, habitat specificity and 
geographic range (Table 1 ) .  
Table 1: Seven forms of rarity (Rabinowitz, 1 98 1 )  
Geographic distribution Wide Narrow 
; . . .. . . . . ... .. . ...... . ... . 
Habitat specificity Broad Restricted Broad Restricted 
Large popUlation 
somewhere 
Small populations 
everywhere 
3 
Table 1 has eight categories, but the one for plants with wide geographic distribution, 
broad habitat specificity and a large population somewhere are unlikely to be  rare. 
Fiedler and Ahouse ( I 992) simplified the spatial scale to one variable and introduced a 
temporal dimension (Table 2) . They list a hierarchy of factors that may prove important 
in determining rarity for each category. 
Table 2: Four categories of rarity in vascular plants (Fiedler and Ahouse, 1992) 
Temporal persistence Short Long 
. ., . .. , . . 
Wide spatial distribution 
Narrow spatial distribution 
.5. 
Numerous contributing factors have been identified as possible  causes of rarity in studies 
conducted to date. The multiplicity of causes thought likely to contribute to the rarity of 
different species has led to the suggestion that all species may be idiosyncratic (Fiedler, 
1 98 6). 
Smal l populations and ext inct ion 
'We need not marvel at extinction; if we must marvel, let it be at our own presumption 
in imagining for a moment that we understand the many complex contingencies on which 
the existence of each species depends' 
C. D arwin ( I  872) 
There are many reasons why a population may be small. Harper ( 1 979) summarised 
them, as follows: 
.:. The available sites are few and separated by distances beyond a speCIes normal 
dispersal ability . 
• :. The carrying capacity of the site is low . 
• :. The habitability of the site is of short duration because of successional displacement . 
• :. Colonisation is in its early stages, and full exploitation of the site has not occurred . 
• :. Catastrophes of various kinds 
Species with small populations are thought to have a greater chance of becoming extinct 
4 
than others. However, there i s  still a large amount of variation in probability of 
extinction predictions (Gaston, 1 994). Not all rare species exist in small p opulations, 
just as not all species with consistently small population size are considered rare. Plants 
have quite different life history characteristics than animals and the generalisations may 
not always apply. The diversity of mating systems from self-fertilisation to complete 
outcrossing, seed dormancy and the reliance upon animals for pollination and seed 
dispersal are some unique characters (Schemske et al. 1 994). Plants that are self­
compatible and that self fertilise are not susceptible to many of the factors that were 
identified by Soule ( 1 983) as possibly contributing to extinction of local populations 
(Table 3 ). As Table 3 suggests, many factors can affect extinction probabilities as well 
as small population size. 
Table 3. Possible factors contributing to the extinction of local populations (from Soule, 1 983) .  
Rarity (low density) 
Rarity (small, infrequent patches) 
Limited dispersal ability 
Inbreeding depression 
Loss of heterozygosity 
Founder effects 
Hybridisation 
Successional loss of habitat 
Environmental variation 
Long term environmental trends 
Catastrophe 
Extinction or reduction of mutualistic populations 
Competition 
Predation 
Disease 
Hunting and collecting 
Habitat disturbance 
Habitat destruction 
Catastrophes are able to cause rapid population decreases that are often unpredictable. 
These include  physical factors (hurricanes, droughts), biological factors (pest invasion, 
5 
epidemics) or human induced changes (Mangel and Tier, 1 994) . Menges ( 1 990) notes 
the importance of catastrophic events in a population viability analysis of Furbish's 
lousewort, finding that they dominate population viability estimates. Without 
catastrophes random variation in demographic parameters will see population numbers 
fluctuate over time. When population size is small, these population fluctuations may 
include zero (i . e. population extinction) (Rabinowitz et al. 1 989). 
It is expected that population density and geographic range would vary over time, hence 
the temporal component in species rarity. However, there is evidence suggesting range 
and abundance are persistent species characteristics i .e .  some taxa are more prone to 
extinction than others (Lawton, 1 993) ,  the corollary of that being that some are more 
likely to persist than others. Density and range are considered linked to the species '  
fundamental niche breadth, an evolved species trait (Brown, 1 984). A good example of 
this is found in New Zealand Myosotis species, as local density and range size are 
persistent species characteristics. This line of thought implies that there is a phylogenetic 
component to the types of rarity patterns found within genera and several researchers 
have studied this. Rare plants are under represented in some families (Rosaceae) and 
over represented in others (Scrophulariaceae, Lamiaceae) (Schwart, 1 993) .  Another 
study found disjunct taxa within genera of herbaceous perennials had range sizes 
significantly correlated with each other (Ricklefs and Latham, 1 992) . A further study has 
found the families, that have more than an average number of rare species, are different 
in Australia, New Zealand and North America, thought to b e  due to different speciation 
histories in different landscapes (Westoby, pers. comm.) .  In New Zealand, our 
threatened species are mostly in the B oraginaceae, Scrophulariaceae, Asteraceae, 
Orchidaceae, and Poaceae (de Lange and Norton, 1 998). Although genus and family 
size accounts for some of this pattern, not all can be explained in this way (see de Lange 
and Norton, 1 998). 
As well as the size of the population, other information can be used to assess extinctio n  
threats. B ond ( 1 995) considered aspects of reproductive biology were critical i n  
determining extinction probabilities. He found extinction risk to be greatest when the 
risk of pollinator or disperser failure, reproductive dependence on the process and 
demographic dependence on seeds are all high (Bond, 1 995) .  
6 
Persistence 
Understanding adaptations rare speCIes display that reduce their vulnerability to 
extinction is an area that requires research (Gaston, 1 994). In studies of rare and 
common congeners, the differences found in the rare species are often considered 
adaptive traits that have evolved to cope with the state of rarity. These differences could 
be evolved adaptations to deal with rarity but there could also be other mechanisms 
involved (Kunin and Gaston, 1 993) .  Often rarity is studied by ecologists and species are 
considered in ecological rather than evolutionary time; the species, though, is an 
evolutionary concept (Harvey, 1 996) . Species' success or lack of it i s  often studied in 
terms of their traits or characteristics which make them more or less successful under 
particular ecological circumstance s  but the traits are not randomly distributed. Therefore 
it is important to take phylogeny into account when making interspecific comparisons 
(Harvey, 1 996). The newer phylogeny based tests used in conjunction with interspecific 
comparisons should be able to tell the difference but this requires knowledge of 
phylogeny and ancestral states (Maddison, 1 990) . Unfortunately this is not an easy 
undertaking, as there are very few groups with resolved phylogenies. 
Sparse species (large range sizes and nowhere common) are possibly important in the 
study of persistence (Rabinowitz et at. 1 986). Predicting the population size required to 
ensure high probability that a species will persist has limitations and different values can 
be obtained depending on the type of model involved (Stacey and Taper, 1 992). 
Theorists work out probabilities and estimate times to extinction (e.g. Roughgarden, 
1 97 5) but in the real world there are some well documented cases of small populations 
persisting at very low densities e .g .  some New Zealand birds (Craig, 1 99 1) which are at 
odds with any of the theoretical projections. Stacey and Taper ( 1 992) suggest two 
alternatives to the study of persistence; one is to follow the fate of a recently declining 
population due to human disturbance and determine population level parameters most 
sensitive, the other is to look at species that naturally occur in small, highly fragmented 
populations (i . e .  sparse species) . These species have managed to persist through time 
and have successfully solved the hazards of small population existence. As such, these 
may be model systems from which we can work out how small populations are viable 
(Stacey and Taper, 1 992) . This approach has been taken with woodpeckers (Stacey and 
Taper, 1 992), bighorn sheep (Berger, 1 990) and sparse prairie grasses (Rabinowitz and 
7 
Rapp, 1 984). Rabinowitz and Rapp ( 1 984) found sparse specIes are more likely to 
persist if they are good competitors. Further, sparse species were found to have a 
buffered reproductive response, considered to be a mechanism that o ffsets the 
demographic stochasticity, a hazard of small populations (Rabinowitz et at. 1 98 9). 
Sparse species have been found to have a lower potential for rapid increase (Westoby, 
p ers. comm.) .  
Conservation and rarity 
Rarity and conservation are invariably connected as rare species are thought to have a 
greater chance than common species of becoming extinct. The ultimate fate of small 
populations, their persistence or extinction, is of primary concern to conservationists. A 
key issue in this regard is that species can be rare in different ways. Not all rare species 
are threatened with extinction. Individual species characteristics will affect the ability of 
the population to persist, but ultimately chance events may determine persistence. This 
knowledge has relevance to the process of categorising, classifYing and prioritising rare 
species for threat assessment. 
The reproductive biology of rare plants 
An important aspect in the study of rare plants is the understanding of their reproductive 
biology. The mating system determines the genetic structure and evolutionary potential 
of plant populations (Allard, 1 975) .  It is important initially, to identifY the breeding 
system for the assessment of the status of any rare plant (Hamrick et at. 1 99 1) .  Plants 
with different breeding systems are likely to have different population structures. Some 
species are highly selfing, some have mixed mating syndromes, and others are 
predominantly outcrossing. S elf-pollinators can grow, reproduce and colonise a new 
area by the germination of just one seed. They can easily achieve reproductive isolation 
and do not require the presence of others to successfully reproduce and persist. 
Therefore small popUlation size is not necessarily a sign that the species is rare or 
threatened. Obligate outcrossers or self-incompatible plants require local population 
densities at levels that ensure a supply of cross pollen and attract vectors, if required, to 
achieve pollination. Therefore, to be successful, they need population sizes considerably 
larger than selfing species. 
8 
Aspects of reproductive biology have been linked to rarity III several studies (e.g. 
Rabinowitz and Rapp, 1 98 1 ;  Karron, 1 987a; Kunin and Shmida, 1 997; Quinn et al. 
1 994). Breeding system, pollination ecology, dispersal ability and vegetative 
reproduction are important factors in determining plant distributions .  Other factors, such 
as environmental constraints, and the evolutionary and recent history of populations will 
affect abundance and place limits on distributions. However, it is difficult to prove that 
particular factors have caused the rarity of species without conducting experimental 
manipulatio ns and studies have generally provided  correlational rather than causal 
explanations (Gaston, 1 994). 
Rare-common d ifferences 
A number of studies have focused on comparisons of life history traits between rare and 
common congeners. Despite the inherent problems associated with the study of any rare 
organism (i.e. lack of data) the comparisons have found systematic differences between 
these pairs of species (e .g. Rabinowitz, 1 978;  Rabinowitz and Rapp, 1 98 1 ;  Landa and 
Rabinowitz, 1 98 3 ,  Rabinowitz et al. 1 986;  Karron, 1 987a & b; Kunin and S hmida, 
1 997). Recurrent patterns have emerged of species traits that are non-randomly 
distributed across a wide range of organisms (Kunin and Gaston, 1 993) .  An entire book, 
The Biology (if Rarity: Causes and consequences (�f rare-common d�fferences, (Kunin 
and Gaston, 1 997), has been produced on this topic alone. While the editors 
acknowledge a) that many different mechanisms can account for the similar patterns 
observed and b) that there are difficulties in determining the primary mechani sm 
involved, these differences are consistently appearing in cross-species comparisons 
(Gaston and Kunin, 1 997). Interestingly, when compiling these studies for meta­
analysis, the different types of rarity are not taken into account and yet these patterns still 
appear. Whatever mechanisms are involved, rare species that have been able to persist 
are expected to have traits that allow them to do so in the rare state (Kunin and Gaston, 
1 993) .  
From these studies, some broad generalisations can be made regarding the reproductive 
traits of rare plants. Rare species are biased away from outcrossing and sexual 
reproduction (Kunin and Gaston, 1993). Kunin and Gaston ( 1 993) reviewed the studies 
of rare and common species with respect to dispersal and reproductive effort from which 
they determined the fol lowing main points. Rare plants tend to have: 
9 
• lower levels of self incompatibility 
• a bias toward asexual reproductive pathways 
• lower overall reproductive effort 
• poorer dispersal ability 
Some problems have been identified with the methods used in some of the studies, such 
as the intercorrelation of traits (e. g. reproductive effort and dispersal distances are highly 
correlated) and non-independence of the traits of related species (Kunin and Shmida, 
1 997). Another problem cited by Kunin and Shmida ( 1 997) was that only a single 
measure of rarity was used in each study. Plants can be rare in different ways and at 
different spatial scales. Some studies are of point endemics with dense local populations, 
while others are of sparse taxa with low densities and wide geographic ranges. 
Breedi ng system and rarity 
Population structure and mating system interactions have been studied in both 
experimental and natural populations of plants (Sampson et at. 1 989) and reviews have 
been conflicting regarding any correlation between breeding system and rarity. For 
example Ellstrand ( 1 992) makes the point that rarity of a species is not closely correlated 
with its breeding system, although many rare species are obligate outcrossers. Karron 
( 1 987b) found no significant relationship between breeding system and geographic range 
in the genus Astragalus. In Quinn et at. ( 1 994), in a study of scarce British plants, 
obligate outcrossers were found to be significantly more aggregated than those able to 
self-pollinate. Pollination effects probably operate at small spatial scales (e.g. Diplotaxis 
erucoides in Kunin, 1 992) . The disparity of scales used to measure rarity in different 
studies was recognised by Kunin and Shmida ( 1 997). They used three measures of 
rarity, local density, regional abundance and global distribution in a study of 
Mediterranean annual crucifers (Kunin and Shmida, 1 997). They found breeding systems 
are related to regional- and global-scale measures only when local density is left out of 
the analysis so, although these measures are themselves related, they are not 
interchangeable (Kunin and Shmida, 1 997). It may be that abundance measures have 
been made at different scales in different studies and this has caused the disagreements 
over the relationship between breeding system and rarity (Kunin and Shmida, 1 997) .  
1 0  
Po l l i nat ion b io logy 
Burd ( 1 994) reviewed studies of pollen limitation in determining the role pollen 
limitation in fruit and seed production in flowering plants. He found significant pollen 
limitation at some times or at some sites in 62% of the 258 species included in the study 
(Burd, 1 994). There was variation in the levels of pollen limitation observed at different 
times of the year and in different populations which suggests pollination events are not 
constant (Burd, 1 994) . Generally, self-incompatible species gain greater b enefit from 
supplemental pollinations than self-compatible species (Burd, 1 994) . Burd ( 1 994) 
suggests the best use of resources spread among ovules, pollen and pollinator attraction, 
is to invest in more flowers or ovules per flower than would normally be pollinated in 
order to take advantage of chance fluctuations that bring large amounts of pollen. This 
means that pollen limitation is likely and that flowering plants commonly mature fewer 
seeds and fruits than flowers and ovules produced (Burd, 1 994) . 
A subsequent analysis of the same species was conducted by Larson and Barrett (2000) 
to determine whether pollen limitation was correlated with particular life-history traits 
and ecological conditions. Although herbaceous, nectariferous and temperate species 
were found to be significantly less likely to be pollen limited in the initial comparative 
analysis, when phylogeny was corrected for, although the trends remained the same, 
results were not significant (Larsen and Barrett, 2000). 
In self-incompatible or obligate outcrossing species, the plants growing at low local 
density are more likely than those growing at high density to be pollination-limited in 
their reproductive success (Kunin 1 992, 1 993) and they are also more likely to be self­
compatible (Kunin and Shmida, 1 997). Theoretically population density and outcrossing 
rates are positively correlated (Karron et al. 1 995) .  
Rare species may be more likely to evolve to adopting a species-constant pollinator since 
a generalist will bring largely inappropriate pollen (Kunin and Iwasa, 1 996). However, 
Karron ( 1 987a) found generalists pollinated restricted species of Astragalus. Several 
other restricted species have been found to be generalist-pollinated as well (Karron, 
1 987a) . One possibility suggested was that pollinator specialisation is unlikely to either 
evolve or be maintained because a small population can only sustain a small number of 
individuals (Karron, 1 987a). 
1 1  
Strong selection pressures would be expected for traits that attract pollinators both in 
terms of quality (i .e .  specialist rather than generalist) and quantity (Kunin and Shmida, 
1 997). This has been confirmed in a study of crucifers, which found that self­
incompatible species have particularly showy flowers compared to their self-compatible 
counterparts (Kunin and Shmida, 1 997) . Another way to attract pollinators is to have 
large floral displays. However, a study, which examined the response of insect 
pollinators to variation in flower number on Myosotis colensoi, and Mimulus guttatus 
found pollinators exploited flowers equally, regardless of size of display (Robertson and 
Macnair, 1 995). Ohashi and Yahara ( 1 998) found that the visitation rate of bumblebees 
to Cirsium purpuratum was a decelerating function of floral display (i.e .  as floral display 
size increased, there was an increased visitation rate per plant but it was at a slower 
rate). 
Self-fertilisation can be selected for in particular circumstances .  In changeable 
environments, as population size varies and therefore possible mates, so too can 
pollinator availability such that when population size is low, selfing individuals are 
selected for (Karron, 1 99 1 ) .  The ability to self-pollinate may be advantageous when 
pollinators are scarce and disadvantageous when they are abundant if there is high 
inbreeding depression (Robertson et al. 1 994). In a study of annual crucifers the rare 
species tended to display more extreme values for floral traits than common ones with 
the same breeding systems (Kunin and Shmida, 1 997), which does imply disruptive 
selection i s  occurring. 
D ispersa l  ab i l ity 
The dispersal ability of species is expected to have an effect on their distributions. 
Rabinowitz ( 1 978) found diaspore weight and abundance are positively correlated in 
prairie grasses, and suggested the most likely reason was that rare species seeds are 
adapted for longer-distance dispersal as they are colonisers of spatially and temporally 
rare micro sites. Further work conducted in this respect found dispersal ability negatively 
correlated with abundance (Rabinowitz and Rapp, 1 98 1 ) . Oakwood et al. ( 1 993) found 
a positive relationship between dispersal ability and range size in three ecological regions 
of Australia. Quinn et al. ( 1 994) also found dispersal ability was correlated with 
distribution pattern of scarce British plants. However, this has since been refuted by 
Thompson and Hodgson ( 1 996) who, u sing the same taxa, a different classification of 
1 2  
dispersal in space (i .e. how far they disperse), and new data on dispersal in time (i . e. 
persistence in the seed bank), found no relationship between distribution and dispersal 
ability. Thompson and Hodgson ( 1 996) believe habitat loss i s  the major determining 
factor in the distributions of plants in Britain. Further investigation is required as there 
are other factors involved in determining distributions. There may be different regimes 
operating on the floras of different countries. There is a widely held view amongst 
population biologists that plant population growth is not limited by seed production. 
Crawley ( 1 990) concluded that plant population growth is more likely to be limited by 
environmental factors such as micro site availability than by seed production. Bawa and 
Beach ( 1 98 1) believe plant reproductive success is rarely limited by pollination events. 
However, a recent review of seed limitation studies found 50 % of augmentation studies 
and 5 3  % of introduction studies showed evidence of seed limitation occurring (Turnbull 
et al. 2000). 
Genetics 
The genetic theories of Sewell Wright ( 1 93 1 )  stimulated concepts that highlighted the 
genetic diversity or homogeneity of rare species. The individuals of rare species were 
thought to have less genetic variability, more homogenous genomes and consequently 
the spread of deleterious genes will be more rapid within their small populations (e.g. 
Wright, 1 95 6, Huxley, 1 963). 
Conserving the evolutionary capacity of species by preserving their natural levels of 
genetic diversity is one goal of conservation biology. A primary focus of conservation 
genetic research has been to determine the levels of genetic variation in rare species. 
Mutation, natural selection, migration and random genetic drift are the four evolutionary 
forces which interact with an organism's recombination system that account for the way 
in which genetic variation is distributed among individuals within populations and among 
populations within regions (Barrett and Kohn, 1 99 1). 
Theory predicts that widespread, long-lived, wind pollinated, outcrossers maintain more 
genetic variation within their populations than species with other trait combinations 
(Hamrick et al. 1 99 1). Data has been gathered and analysed from studies of genetic 
diversity to see if any generalisations can be made. Genetic diversity within and among 
populations has been found to be significantly influenced by the breeding system 
1 3  
(Hamrick et al. 1 979; DeMauro, 1 993). Species with different breeding systems, seed 
dispersal mechanisms, geographic ranges, taxonomic status and life forms generally have 
different levels of diversity within and among their populations (Hamrick and Godt; 
1 996). Life form, and breeding system in particular, has highly significant influences on 
levels and distribution of allozyme genetic diversity in seed plants (Hamrick and Godt, 
1 996). Specifically, outcrossing and woody plants had more overall genetic diversity and 
less interpopulation variation (Hamrick and Godt, 1 996). 
It i s  not surprising that these life history traits have been found to influence genetic 
diversity. There are well known associations between breeding system and life form i .e .  
between selfers and the annual habit and between outcrossers and the perennial habit 
(Cl egg and Brown, 1 983) .  Kunin and Shmida ( 1 997) found significant interaction effects 
between breeding system and geographic range. There was a positive correlation 
between geographic range and local abundance in a wide range of organisms (Brown, 
1 984). Therefore, many of these traits may themselves be highly correlated. This 
highlights both the complexity and importance of understanding breeding system 
interactions with the state of rarity. 
Geneti c  threats 
Generalisations aside, genetic considerations are important in a couple of areas. Self­
incompatible plants can become endangered through the loss of alleles at self­
incompatibility loci that can cause direct threats to population persistence through 
reproductive failure (De Mauro, 1 993). If a common, sexually compatible species is 
sympatric with a rare species, then the rare taxa may be vulnerable to extinction through 
hybridisation (Ell strand, 1 992) . 
Inbreed i ng depression 
Although some rare plants occur in large populations, many exist in small, sometimes 
isolated populations. One of the possible effects of small population size is inbreeding 
depression which is a comparative term given to the relative reduction in fitness of selfed 
compared with outcrossed offspring (Barrett and Kohn, 1 99 1 ) .  The most famous 
product of the genetic emphasis on conservation was the "fifty/five hundred" rule 
(Franklin, 1 980). This was considered the minimum population size required to ensure 
short- and long-term viability, (Ne of 50  and 500 respectively), determined by calculating 
1 4  
inbreeding depression coefficients (Holsinger and Vitt, 1 995) .  Inbreeding effects on 
fitness in plants will depend on the diverse array of breeding systems (Charlesworth and 
Charlesworth, 1 987) and may not depend on population size. Species that occur 
naturally in small, isolated populations may be adjusted to inbreeding effects in their 
genetic make up. Their mating systems may have adjusted to allow for the genetic 
consequences of rarity (Barrett and Kohn, 1 99 1) .  When historical evolutionary patterns 
are very different from recent ones, as for those that have naturally large populations that 
have suffered recent declines, problems may arise (Huenneke, 1 99 1) .  Individuals may be  
unable to  adjust quickly enough to their altered circumstances. 
There have been a lot of theoretical and experimental investigations into the significance 
of inbreeding and heterosis on fitness. Generalisations are that inbreeding depression 
usually occurs in outcrossing plants, is less severe in partially selfing species and can be  
absent in  species with high selfing rates (Lande and Schemske, 198 5 ;  B arrett and Kohn, 
199 1). However, actual tests of the theory do not always prove the case. In some 
studies, the theory was confirmed but in others inbreeding depression was found to occur 
in species that frequently self-fertilise (Barrett and Kohn, 1 99 1 ) .  
Mating system evolution has largely been considered within the realm of population 
genetics (Holsinger, 1 996) . The maintenance of outcrossing individuals in populations is 
thought to be due to high levels of inbreeding depression (Charlesworth and 
Charlesworth, 1 987) .  Therefore, inbreeding carries out an important genetic function in 
maintaining the range of plant-mating systems. The means by which genetic transmission 
is achieved in outcrossers is via their pollinators and, subsequently, their offspring. 
Plant-pollinator interactions and their consequences for seed set are generally studied 
from an ecological rather than genetic p erspective (Holsinger, 1 996; but see Lloyd, 
1979) .  The pollen transfer patterns will be interacting with, and influencing the means by 
which genetic transmission is  accomplished within different mating systems (Holsinger, 
1 996). Further knowledge gathered through empirical studies of pollination biology will 
assist our understanding of mating system evolution. 
There have been a great number of genetic studies in recent times, with the development 
of biochemical and molecular techniques that have enabled levels of genetic diversity to 
be quantified. The idea that rare plants are genetically depauperate and the theory behind 
it, still stands, although results have not universally supported the theory. Population 
1 5  
SIze, while an important factor, clearly is not the only factor determining genetic 
diversity. The evolutionary history of a population will have impacted on the level of 
genetic diversity within it. The level of genetic variation within a species provides the 
potential for evolutionary change (Huenneke, 1 99 1 ) .  The breeding system is the 
mechanism for passing on this variation. Levels of genetic diversity are significantly 
influenced by the breeding system (Hamrick et al. 1 99 1 ) .  
S imilarly, current theory regarding the effects of habitat fragmentation predicts that 
reduced size and increased isolation of populations will lead to reduced genetic variation 
through genetic drift, inbreeding, lower levels of gene flow and local population 
extinctions (Gilpin, 1 99 1 ). A review of recent studies of the population genetic 
consequences of habitat fragmentation for plants has found that although the data 
generally confirm reduced population size is accompanied by reduced genetic variation, 
not all fragmentation events lead to genetic losses and in some cases fragmentation 
appears to increase gene flow among remnant populations (Young et al. ] 996). 
After a couple of decades of research into plant conservation genetics and population 
viability, there are few generalisations that can be made about the genetics of rare plants .  
Genetic considerations are important for endangered self-incompatible plants because 
the loss of alleles at self-incompatibility loci may pose direct threats to population 
p ersistence (DeMauro, 1 993). Hybridisation of endangered species with common 
relatives may result in genetic assimilation and loss of the rare taxon (Ell strand, 1 992; 
Rieseberg, 1 99 1 ) . However apart from these two situations, genetic concerns may be 
largely inappropriate when assessing the status of rare plants. If populations are 
ecologically viable, then they may be large enough to handle any risks of loss of genetic 
diversity (Lande, 1 988). This line of thought has lead to the suggestion that there is no 
need to be concerned about genetic threats to the p ersistence of rare species that have 
always been rare (Holsinger and Vitt, 1 995) .  The populations that have suffered recent 
losses, particularly those with previously widespread distributions, are likely to be  
relatively more at risk than those that have always had small populations. 
Vegetative reproduct ion 
Rare plants are biased toward having asexual reproductive pathways (Kunin and Gaston, 
1 993) .  When population size is low or variable, selection for individuals with the 
1 6  
capacity to reproduce vegetatively may be similar to that for selfing mechanisms. There 
may be the advantage that the sprouting of a rosette from an existing plant, which 
effectively increases the plants' size and reproductive capacity, may improve its ability to 
attract pollinators and sexually reproduce. It also may simply be a safer means of 
reproduction. 
In conclusion, the overriding importance of understanding the reproductive biology of 
rare plants i s  emphasized .  In particular mating system and pollination biology are maj or 
factors determining vulnerability of rare plants in different situations. 
considerations of endangered species are required in only a few cases. 
New Zealand Myosotis L. (Boraginaceae) 
Genetic 
Forget-me-nots, Myosotis specIes, belong to a cosmopolitan genus within the 
Boraginaceae and have a worldwide temperate distribution. Current references for the 
total number of species are inaccurate. Mabberly ( 1 987) puts the worldwide distribution 
at 50 with 4 1  of these occurring in Europe. However, there are 34 New Zealand species 
described in the Flora of New Zealand (Allan, 1 96 1 ), although Webb et al. ( 1 990) put 
the number of New Zealand species as 47 and the worldwide total at about 1 00. This 
may still increase as the numerous undescribed taxa are given taxonomic treatment. 
With the inclusion of all undescribed taxa, Druce ( 1 993) inflates the New Zealand total 
to about 60 species. 
The most recent taxonomic treatment of the New Zealand species is in the Flora of New 
Zealand by Dr Lucy Moore (Allan, 1 96 1 ) .  Previous classifications of the genus initially 
divide it on the basis of anther position in relation to corolla scales (see Robertson, 1 989  
for a review). Moore (Allan, 1 96 1 )  makes the comment that it is not necessarily a 
natural division (p . 807), but retains it as the initial division of the genus.  Some taxa are 
recognised on this basis with little else differentiating them. For example, it i s  the only 
readily distinguishable character difference between Myosotis venosa and Myosotis 
forsteri (Robertson, 1 989). Myosotis lyallii may be synonymous with Myosotis elderi 
for the same reason (Robertson, 1 989). 
Grau and Schwab ( 1 982) proposed a new infrageneric classification based on 
morphological characters of pollen, stigma, corolla scales, and anther tips .  They split the 
genus into two sections, Myosotis and Exharrhena. The Exharrhena section is  split into 
1 7  
two groups, the discolor group,  which contains some European and one African species, 
and the austral group, which contains the New Zealand taxa. New Z ealand is the 
southern hemisphere centre of diversity for the genus (Winkworth et al. 1 999) .  In 
addition to the New Zealand taxa the austral group contains four other species; two in 
Australia, one in South America and one in New Guinea. 
F lora l  morphology and pol l ination b io logy in New Zeal and Myosotis 
New Zealand Myosotis species studied in detail have been found to have different mating 
types that depend, in part, upon the degree of anther exertion displayed and length of the 
style in relation to the position of the anthers (Robertson and Lloyd, 1 99 1 ) . Moore (in 
Allan, 1 96 1 )  states that " . . .  exserted anthers are little known in the genus outside  NZ" . 
The general character of the genus here differs in many respects from the Northern 
Hemisphere relatives. Several aspects of the reproductive biology of selected taxa have 
been studied . All species studied so far have been found to be fully self-compatible, but 
differ in their ability to set seed autonomously (Robertson, 1 989). With the exception of 
M pygmaea vac minutijlora, which was not dichogamous, all species studied to date 
have incomplete dichogamy in the form of protogyny (Robertson and Lloyd, 1 99 1 ) . One 
species, Myosotis monroi, has precocious buds (sensu Robertson, 1 989), in which 
stigmas are exserted before the bud opens. 
Flowers are hermaphroditic, carried on scorpio id cymes and each is able to produce up 
to four nutlets. Three main types of flowers are recognized in New Zealand Myosotis; 
tube, funnel and brush blossoms (Robertson, 1 989). 
Tube blossom: These flowers usually have a narrow corolla tube of variable 
length. The tube is framed by conspicuous corolla scales, with flat, free corolla lobes (fig 
1 ,  left) . Filaments are more or less short carrying anthers near the top of the tube, but 
the degree of inclusion/exertion varies. 
Funnel blossom: These flowers have a wider corolla tube that is more or less funnel 
shaped. The corolla lobes are spreading rather than flat and often fused above the scales 
giving the flower a funnel shape (fig 1 ,  centre). 
1 8  
Brush blossom: These flowers have a narrow corolla tube, with a nm of 
conspicuous scales and free flat corolla lobes, but differ from the tube blossom type in 
having anthers and stigma on long exserted filaments and styles (fig 1 ,  right) . 
Figure 1 :  Examples of the three floral forms recognised within New Zealand Myosolis. M traversii var. 
traversii (left) has tube blossom flowers, M arnoldii (centre) has funnel blossom flowers and M brockiei 
has brush blossom flowers. Photos by Bruce Sunnex, B i l l  Maicolm, and Alastair Robertson. 
CONSERVATION 
Within the ew Zealand group there are a large nwnber of extremely local ized taxa, 
which are often restricted to a single mountain or range, and the genus contains some 
very rare species. By contrast, other species have very sparse distributions and although 
they are relatively widespread, they are never common where they occur. Several 
different abundance and distribution patterns or rarity patterns are evident within the 
New Zealand taxa. For example Myosotis Jorsteri is found within about three quarters 
of New Zealand's land area south of l atitude 38°  S (Landcare Research Herbarium, 
Lincoln, hereafter referred to as CHR; Allan, 1 96 1 ). While having a widespread 
distribution, it is often found as a single individual or as two or three plants in a 
population and has only occasionally  been seen in populations as large as 30.  Although 
never common where it occurs, it is not considered threatened in any way. By contrast, 
M concinna, an endemic of the Marino Mountains in north-west Nelson, occurs in a 
very restricted geographic area. Although confined to specific habitats within the alpine 
zone, it is quite common where it occurs. 
A large proportion of the New Zealand taxa in the genus are considered threatened, with 
33% featuring on the latest list (de Lange et a!. 1 999), but are often not wel l enough 
known in the field or are of uncertain taxonomic status (Molloy and Davis, 1 994; 
1 9  
Cameron et al. 1 995). Priority setting and management decisions for their conservation 
are impeded by this lack of knowledge. Six of the Nelson taxa are currently listed as 
threatened in some way. M laeta has been classified as Vulnerable (Cameron et al. 
1 995) but the reappraisal to the newly erected Range Restricted category (de Lange et 
al. 1 999) acknowledges recent survey results; M. brockiei has b een classified as Rare 
(Cameron et al. 1 995), I ( Insufficiently known) (Dopson et al. 1 999) and is now 
classified as Range Restricted (de Lange et al. 1 999); M angustata, M arnoldii and M 
concinna were on the local plant list (Cameron et al. 1 995)  and are now classified as 
Range Restricted (de Lange et al. 1 999). M petiolata var. petiolata has been classified 
as Insufficiently Known since 1 993 (Cameron et al. 1 993 ; Molloy and Davis, 1 994; 
Cameron et al. 1 995;  de Lange et al. 1 999). Due to the large number of threatened 
species within the genus, the Department of Conservation has assigned high priority to 
research in the genus, and have part funded this research in order to find out more about 
this group of rare plants. A report was produced for the NelsonlMarlborough 
Conservancy of the Department of Conservation (Appendix 1 ). 
The aims of the thesis were to investigate several aspects of rarity in New Zealand 
Myosotis. The reproductive biology of several species with a range of floral 
morphologies and rarity types were studied. Mating types were examined in order to 
determine whether pollen limitation was occurring and whether this related to rarity 
patterns. Reproductive failure and population extinction due to Allee effects is a possible 
consequence of Iow population density and size. The influence that local flower density 
and population size had on reproductive output in out-crossing species was compared 
with selfing taxa. The effect on population dynamics was considered. Precocious stigma 
presentation was investigated in a geographically restricted species, M monroi. The 
effect of precocious bud development and a prolonged initial female phase on pollination 
success was considered. As the genus contains several different types of rarity and many 
threatened species, one of the aims of this thesis was to investigate whether certain 
morphological traits had any association with the range of rarity patterns seen. Species  
distributions, population disjunctions and local densities were compared with floral 
morphologies, pollination requirements, potential dispersal aids (seed size and some 
calyx properties), and life-history traits (e.g. how long lived each species is). Species  
limits in  the M forsterilM. venosa species complex were explored to  critique Moore' s  
treatment of the genus (in Allan, 1 96 1 ). Specifically, the use of anther exertion as an 
20 
appropriate taxonomic character with which to split the genus was explored . 
2 1  
CHAPTER TWO 
Mating types, herkogamy and rarity in  six species of New Zealand 
Myosotis L.  (Boraginaceae) 
Abstract 
The reproductive biology of six species of Myosotis was studied. New Zealand Myosotis 
species studied to date fall into either one of two mating types based on the degree of 
herkogamy exhibited by the flowers. Species with flowers that are herkogamous 
throughout the life of the flower require pollinators to set seed while those that are not 
herkogamous at some stage during anthesis are able to self-pollinate autonomously 
without the need of a vector. Details of the mating types operating in six species of 
Myosotis are presented .  Hand pollination tests showed all six species are fully self­
compatible. The four species with brush or funnel blossom flowers, Myosotis monroi, 
M brockiei, M laeta and M macrantha, required pollinators to transfer pollen and to set 
seed. The two tube blossom species, M. forsteri and M. tenericaulis were able to set 
seed autonomously without pollinators. These mating types were directly related to the 
degree of herkogamy displayed. Pollen limitation was found to occur in the four 
pollinator-requiring species but not in the two autonomous species. The associatio n  
between mating types and rarity patterns are discussed. Results are examined in the 
context of theories regarding mating system evolution with respect to New Zealand 
Myosotis. 
Introduction 
New Zealand Myosotis L. (Boraginaceae) is a genus of relatively short-lived, herbaceous 
species that occurs from the salt turfs of the coastal zone to the fellfields of the high 
alpine zone. Within the group there are many rare species, encompassing several 
different types of rarity, and a range of floral forms. Three main types of floral syndrome 
have been recognized in New Zealand Myosotis; tube,  funnel and brush b lossoms 
(Robertson, 1 989) (Fig. 1 ,  Chapter one). The brush blossom taxa are unique to New 
22 
Zealand as Moore (in Allan, 1 96 1 )  states, " . . .  exserted stamens are little known in the 
genus outside (New Zealand)". Robertson ( 1 989) has investigated the reproductive 
biology of six species of New Zealand Myosotis; M colensoi, M. jorsteri, M uniflora, 
M. australis var. lytteltonensis, M. pygmaea var. minutiflora and M spathulata. In 
some species vectors are required for pollination to be carried out. I n  others, the 
receptive stigma is in contact with the anthers at least some of the time. A variety of 
forms of herkogamy and incomplete dichogamy were found which influences the 
parentage of seeds and represents different stages along the outcfOssing-selfing 
continuum (Robertson and Lloyd, 1 99 1 ) . Species have been found to have different 
mating types that depend, in part, upon the degree of anther exertion displayed and/or 
the length of the style in relation to the anthers (Robertson and Lloyd, 1 99 1 ) . A range of 
mating types from complete autonomy to complete pollinator-dependence is found 
within the tube-flower group (Robertson and Lloyd, 1 99 1 ) . The species included in this 
study encompass all three blossom types: the brush, funnel and tube. 
An important aspect in the study of rare plants i s  to understand their reproductive 
biology. The mating system determines the genetic structure and evolutionary potential 
of plant populations (Allard, 1 975) .  Wright ( 1 93 8) discussed the evolutionary 
importance of breeding system and population size on speciation. Plants with different 
breeding systems and population structures are under very different selection regimes. In 
predominantly outcrossing species, individuals that occur in small isolated populations 
are likely to undergo more rapid evolutionary change than when they occur in large 
populations (Wright, 1 93 9) .  Selection that occurs in selfing species on the other hand, is 
not affected by size or isolation of population and results in groups of basically 
genetically identical individuals (Wright, 1 93 9) .  
Herkogamy and D ichogamy 
There are two opposing forces at work on hermaphroditic flowers that influence their 
morphology. On the one hand there is a strong advantage in having the two pollination 
surfaces  in the same position, thereby increasing efficiency of pollen transfer, while on 
the other hand, there is the opposing need to avoid interference between receiving and 
exporting pollen (Webb and Lloyd, 1 986). Dichogamy, the temporal separation of 
anthers and stigmas, and herkogamy, the spatial separation of anthers and stigmas are 
two methods hermaphrodites use to avoid interference during the reproductive season 
23 
which have the additional utility of improving outcrossing potential (Webb and Lloyd, 
1 986) .  The degree of dichogamy and/or herkogamy a flower exhibits influences the 
parentage of seeds (Robertson and Lloyd, 1 99 1 ) .  F or species that are fully self­
compatible, physical methods such as herkogamy and dichogamy can reduce levels of 
self-pollination (Garnock-Jones, 1 976) .  There are a range of types of dichogamy and 
herkogamy described to date (see Lloyd and Webb, 1 986 and Webb and Lloyd, 1 986). 
Only herkogamy allows both the receipt and dispatch of pollen during a single insect visit 
whereas dichogamous blossoms usually require at least two visits (Webb and Lloyd, 
1 986) .  
The six specIes of Myosotis with tube blossom type flowers that were studied by 
Robertson ( 1 989) were assigned to three categories - 'always herkogamous', 'initially 
herkogamous' and 'never herkogamous' (Robertson and Lloyd, 1 99 1 ) .  The flowers of 
plants always exhibiting herkogamy will require a vector of some sort to achieve 
pollination and fertilization. Of the Myosotis species studied by Robertson ( I 989), the 
flowers of those that were 'always herkogamous' exhibited 'approach herkogamy', in 
which the stigma protrudes beyond the level of the anthers, and is therefore more likely 
to be contacted first by pollinators, making self-pollination less likely (Robertson and 
Lloyd, 1 99 1). The species of Myosotis studied by Robertson ( I 989) that were 
herkogamous at least some of the time, also exhibited incomplete dichogamy in the form 
of protogyny (presentation of stigma before pollen). Protogyny is not as common as 
protandry in angio sperms (Lloyd and Webb, 1 986) .  Webb and Lloyd ( I 986) concluded 
that protogyny is a more successful means of avoiding self-fertilization than protandry 
and will more likely be the type of dichogamy that evolves when the avoidance of self­
fertilization is the selective force. Therefore, the combination of approach herkogamy 
and protogynous dichogamy exhibited by Myosotis species that require vectors to 
achieve pollination will improve their chances initially, at least, of receiving outcross 
pollen. 
Rarity patterns 
Looking at the New Zealand species in the genus there are several different abundance 
and distribution p atterns evident. Many Myosotis species are rare and l ocal, often 
occurring in single,  isolated populations, sometimes in large numbers while others are 
widespread but never common where they occur. For example Myosotis forsteri is 
24 
found within about three quarters of New Zealand's land area south of latitude 3 8° S 
(All an, 1 96 1 ). While having a widespread distribution, it is often found as a smgle 
individual or as two or three plants in a population and has been seen occasionally in 
populations as large as 30 .  By contrast, Myosotis monroi, an ultramafic endemic to 
mountains east of Nelson, New Zealand, occurs in a very restricted area. Although 
confined to a very small range size, it is locally common where it occurs and is usually 
found in relatively large populations of more than 500 flowering individuals .  In between 
these two extremes is Myosotis hrockiei, which has a small range size, but typically 
occurs in small populations of up to 50 flowering individuals .  
The range of rarity types is quite well covered by the genus as are a variety of threat 
classifications. Of the six species in this study two are listed as threatened in some way. 
Myosotis laeta and M. hrockiei are classified as Range Restricted (de Lange et al. 1 999); 
M. monroi, M. jorsteri, M tenericaulis and M. macrantha are not considered 
threatened. 
The aims of this chapter are to determine what mating type is operating in each of the 
taxa by carrying out various pollination experiments. Where some populations are not 
producing the maximum amount of seed possible, hand pollinations are carried out to 
distinguish between resource and pollen limitation in the field. Results are examined with 
regard to rarity patterns and mating type evolution. 
25 
Materia ls and  Methods 
Study taxa , field sites and treatments 
S i x  species o f  Myosotis were c hosen to study their pol l ination req u irements.  F lowers 
are hermaphrodit ic  carried on scorpio id c ymes and are each ab le to produce up to fo ur 
nut lets. 
The species chosen and populations studied were : 
Myosotis brockiei L. Moore et M .  S impson 
Cobb Val ley and Flora Val ley, Nelson, ew Zealand 
Figure 1 :  Myosolis brockiei, Cobb Reservoir, Nelson, ew Zealand. Photo by Brucc SUl lncx.  
This species is confined to a small  area centred in  the Cobb Valley.  Threc popula t ions 
were used for this  study, as  no s ingle  popu lat ion was large enough to enab l e  a l l 
treatments to be carried out .  P l ants are usually fo und on  u l tram afi c  or l imcstone 
outcrops often within forest or at  r iver gorge margins and usual ly bclow t ree l i nc .  A l l  
treatments were carried out o n  separate p lants. F lowers are o f  the brush blossom type. 
lt i s  currently c lass ified as Range Restricted (de Lange et al.  1 999) .  Members o f  the 
Acroceridae were observed pol l i nating flowers at populat ions near the Cobb Rescrvoi r .  
26 
Myosotis laeta Cheesm.  
Red Hi l l s  Plateau, Richmond Range, Nelson, New Zealand. 
Figure 2 :  Myosotis laeta, Red Hills Plateau, Nelson, ew Zealand. Photo Alastair Robertsol1. 
M. laeta occurs in tussock and manuka shrubland of the mineral belt, east of Nelson. 
The population studied is restricted to a relatively small area of the plateau, previously 
burnt, in amongst regenerating manuka. All treatments were c arried 0 ut 0 n s eparate 
plants. F lowers are of the brush blossom type. It is currently classified as Range 
Restricted (de Lange et al. 1 999). Members of the Halictidae were observed pollinating 
flowers at the Red Hills Plateau population. 
27 
Myosotis monroi Cheesm. 
Dun Mountain, Bryant Range, Nelson, New Zealand. 
Figure 3: MyOSOlis monroi, Dun Mountain, Nelson, New Zealand. Photo Alastair Robertson. 
M monroi is an u ltramafic endemic of the mineral belt, which appears sporad ically 
along the ranges east of Nelson, from D'Urvil le Island in the north through to the Red 
Hi l ls in the south. At Dun Mountain, populations occur on the exposed, rocky, treeless 
fel lfield, between 880 and 1 1 00 meters. Few other plants are able to tolerate the 
condit ions of the serpentine environment (Lyon et al. 1 970). All  treatments were 
carried out on separate plants. Flowers are of the brush blossom type. Very l ittle 
pol l inator activity was observed at the Dun Mountain populations. Some rare v isits by 
bumblebees (Bombus sp.) were seen. At the Red Hills Ridge, however, populations of 
which flower about six weeks later in the season, members of the Halictidae, Syrphidae 
and black scree butterfl ies were observed frequently visiting flowers. 
28  
Myosotis macrantha (Hook. F . )  8enth . et Hook. f. 
Mt Mytton, Peel Range, Nelson, New Zealand. 
Figure 4: Myosotis macrantha, Lake Peel, Nelson, New Zealand. Photo Alastair Robertson. 
M. macrantha is a South Island endemic occurring mainly west of the divide (Allan, 
1 96 1 ) . I t o  ccurs 0 n a r ange 0 f g eological s ubstrates but is quite particular regarding 
alti tude, aspect and habitat. The Mt Mytton population is restricted to alpine, l imestone 
outcrops, which are surrounded by tussock grassland. Due to site conditions and plant 
size three poll ination treatments were carried out on the same plant, ( i .e. self, cross and 
pol linator excluded) while the control plants were separate. Flowers are of the funnel 
b lossom type. Robertson ( 1 989) observed moths carrying out pollination at a popUlation 
of this species. Small Diptera were observed in flowers at the Mt Mytton popUlation 
and were also observed in flowers at Lake Peel. 
29 
Myosotis forsteri Lehm .  
Myttons Creek, Cobb Valley, Nelson, New Zealand. 
Figure 5: Myosotisforsteri, Cobb Valley, Nelson, New Zealand. Photo Alastair Robertson. 
This  speci es is found in a variety of habitats and geological substrates in forest or at 
forest margi ns.  This species has been found to be 'initially herkogamous' when the 
reproducti ve biology of plants from a Central Otago population was stud i ed (Robertson 
and Lloyd, 1 99 1 ) . As plants self themselves, self-pollinations were not carried out . All 
other treatments were carried out on separate plants. Flowers are of the tube b lossom 
type. No insects were seen visiting flowers at any of the populations. 
30  
Myosotis tenericaulis Petrie 
Flora Limestone, F lora Val ley, Nelson, New Zealand.  
Figure 6 :  Myosotis tenericaulis, Flora Val ley, elson, ew Zealand. Photo B ruce Sunnex. 
These p l ants occur In a variety of habi tats but are o ften found under l i mestone 
overhangs and at cave entrances. Anthers and st igmas are in c lose contact d uring 
anthesis,  which i ndicates self-p o l l i nat ion w i l l  occ ur. Therefore the sel fi ng treatm cnt 
was not carried out.  A l l  other treatments were caITied out on separate p lants.  F lowers 
are of the tube b lossom type. 0 insects were observed vis i t ing f1owers. 
Treatments 
IJ1dividual  p l ants were e ither caged to excl ude po l l i nators whi le  flowers were i n  bud or 
left open in  the field.  As and when flowers opened treatments were carried out .  
For a l l  species except M. macrantha, plants were assigned to one o f  four  trcat ments :  
1 .  Pol l inator-excluded (caged) and sel f-pol l i nated 
2. Caged and cross-pol l inated 
3 .  Caged and unmanipulated 
4.  Open and unmanipulated = control 
Since M. l7lacrantha usual ly has mUlt ip le  inflorescences, I deci ded to p lace treatm ents I 
to 3 a l l  w i th in  one p lant, but  a different p lant w as used for treatment 4, as I was worri ed 
3 1  
that the bags u sed in the other treatments might deter flower visitors. Flowers of the two 
selfing species, M forsteri and M tenericaulis, assigned to the cross-pollination 
treatment had anthers pinched off with forceps prior to anthesis. It was not necessary to 
remove anthers in the remaining species, as they do not contact stigmas. 
Two to three weeks after treatment, seed set was counted. The developing seeds are 
easily observed in maturing calyces. 
Herkogamy 
Herkogamy was measured in the field using calipers to the nearest O .  1 mm. The distance 
between the stigma and the centre of a randomly chosen anther was measured o n  flowers 
of each species. 
Data ana lysi s  
In each case seed set was expressed as a proportion set out of the total possible, then 
arc sine transformed to better fit the assumptions of the tests performed. ANOV As were 
performed on seed set results to compare treatments for each species. In M macrantha, 
where the three hand-treatments were performed within a plant, I performed two 
analyses. In the first, I used each plant as a block and compared only the three 
treatments these plants received. In the second analysis, I pooled the hand-cross and 
hand-selfed results and compared these to the open-pollinated plants. Multiple 
comparIsons were then carried out to determine which treatments were significantly 
different. 
Using S-Plus, box plots were generated from the seed set data to graphically show the 
results from each treatment and to examine variation. The box plots depict the median 
(central line in each box), 25% and 75% quartiles (upper and lower limits of each box), 
the maximum point within 1 . 5 times the interquartile range from the quartiles (indicated 
by the whiskers), and the outliers (i .e . ,  points greater than 1 . 5 times from the quartiles) 
indicated by lines outside whiskers. 
3 2  
Results 
Po l l i nat ion requirements 
All species with brush or funnel blossom type flowers were unable to set seed when 
pollinators were excluded (Fig. 7 ;  Table 1 ) . Myosotis brockiei, M laeta, M monroi and 
M. macrantha set very little seed when exclusion caged, and therefore require a 
pollinator to achieve much seed set. The two species with tube blossom flowers (M 
forsteri and M. tenericaulis) were able to set high levels of seed when pollinators were 
excluded and do not require a pollinator to achieve seed set (Fig. 8; Table 1 ) .  
Three populations were used for the study o f  M brockiei. Therefore the population was 
included as a block in the ANOVA, and there was a small but significant population 
effect (p=O. 0 1 ;  Table 1 )  as well as  a treatment difference but no population by treatment 
interaction .  
All six species i n  this study are fully self-compatible, at least t o  the seed set stage. 
Flowers set as much seed when pollinated with self or outcross pollen. I did not test 
viability or vigour of seeds produced from self compared with outcross  pollinations, 
therefore can only state with certainty that these flowers are self-compatible to the seed 
production phase. 
Po l len l im itation 
The four vector-requiring species, M brockiei, M laeta, M monroi and M macrantha, 
all showed significant differences between seed set by unmanipulated plants and hand­
pollinated plants (Fig. 7; Table 1 ) . Flowers of unmanipulated plants set significantly 
lower levels of seed than flowers that had been hand pollinated, which suggests pollen 
limitation is occurring. The two autonomous species, M ./orsten and M tenericaulis, 
were never pollen limited .  
3 3  
1 . 1 �------�a---------a�-------------------------r 
0.7 
0.3 
1 .0 
1 
i 
0 5 j 
b 
c 
a 
J 
��acrantha 
Hand crossed Pollinator excluded 
Hand selfed Unmanipulated 
Figure 7: Box p lots of resultant seed set from the pollination treatments carried out on each pol l inator­
requiring species. Treatments that, within a panel ,  share a letter are not significantly difTerent (p<O.05). 
34 
Table 1 :  Results of  the analysis of  the pollination treatments. 
� 
Species Factor df F value P 
�u ••••• _ ............................. nu •• n ••••••• " " _' •• _____ ••• __ .u •• n ..................... ___ •••••••• n ___ ......... _ .......... __ ••• ___ • ____ •••• __ •••• _ 
Myosotis brockiei Population 2 3.48298 0.04 1 7  
Trea1ment 3 1 8.36 1 73 <0.000 1 
Pop:trt 6 0.25232 0 .9550  
Residuals 35 
Myosotis laeta Trea1ment 4 62.30722 <0.000 1 
Residuals 35  
Myosotis monroi Treatment 3 62.94387  <0.000 1 
Residuals 44 
Plant 6 0.47704 0 .8071 
Myosotis macrantha 
Treatment 2 87.97845 <0.000 1 
(within-plant treatments) Residuals 7 
(among-plant treatments) Treatment 1 7. 6 1 343 0 .00 1 2  
Residuals 1 2  
Treatment 2 0. 1 4942 1 6  0.862 1 
Myosotis forsteri 
Residuals 22 
Trca1ment 2 0. 1 67 1 392 0.8472 
A1yosotis tenericaulis 
Residuals 2 1  
There is a greater varIance In  seed set by vector-requiring species than autogamous 
species when plants are open p ollinated without manipulation. Variation decreases for 
these species when flowers are caged to exclude pollinators. There is no difference 
between treatments in variation for the autonomous species. The greater variance in 
seed set by unmanipulated plants suggests individual plants are subject to differing 
degrees of pollen limitation. 
The results for the experiments carried out on Myosotis macrantha were analysed 
differently from the other species. The cross, self and pollinator-exclusion treatments 
were carried out on the same plant while the control data were collected from separate 
plants .  The analysis was carried out in two parts; firstly, the three treatments carried out 
on each plant were analysed separately in order to test for any plant effects (results of 
which are represented by letters above the box-plots). There was not a plant effect. 
Secondly, as there was no significant difference b etween cross- and self-pollination 
treatments, the results were pooled to test hand versus open pollinated seed set for the 
difference (which was significant) . 
3 5  
a a a 
1 .0 E::::::3 ¥ 2 
0.8 
0.6 
0.4 
.--.. 
C 
0 0 .2  t 
0 
Q.. 0.0 Myosotis forsteri 0 l-
Q.. a a a 
...... 1 . 0  � � 2 ID Cl) -0 ID 0 .8  ID 
(j) 
0.6 
0.4 
0.2 
0 .0  Myosotis tenericauiis 
Hand crossed Polhnator excluded Unmampulated 
Figure 8: Box plots of resultant seed set from the pollination treatments carried out on each of the 
autonomous species. Letters indicate significant differences found in statistical analyses (p<O.05). 
Herkogamy and selfing rates 
These results show that herkogamy has a close relationship to selfing rates in these 
species. In order to look at this I have tabulated the herkogamy and selfing rates for 
those taxa for which it has been measured (Table 2). The autonomous selfing rate of 
species (seed set rate by flowers from which polIinators have been excluded, expressed 
as a proportion) is closely related to the degree of herkogamy (spatial separation of 
stigma and anthers) (Fig. 9). Poor seed set occurs when the herkogamy is greater than 0 
mm. 
3 6  
Table 2: Herkogamy and mean seed production in pollinator excluded flowers 
Species Herkogamy Selfing rate 
(mm) (proportion) 
Myosotis brockiei 3 .755 0 .042 
l\{yosotis macrantha 3 . 556 0 ,042 
l\{yosotis colensoi * 3 . 52 0 
Myosotis petio/ata 3 . 5  0,02775 
A1yosotis monroi 1 .688 0.039 
Myosotis laeta 1 . 378 0,02 
Myosotis venosa 0,7 0 . 1 2 5  
Myosotis forsteri (Nelson) 0 0 .95 
A1yosotis tenericauiis 0 0.92 
A1yosotis 'lytteltonensis' * 0 0 , 5 1  
l\{yosotisforsteri (Central Otago) * 0 0.8575 
Myosotis spathulata * 0 0.9 1 75 
l\{yosotis 'minutiflora' * 0 0,9825 
* data from Robertson ( 1 989) 
Herkogamy and selling rate relationship 
I I I 
4 - • 
I 
• 
3 -
-"" i:! 
� 2 - • ill 
if) 
1 -
• 
• • t • 0 
I I I 
0 1 2 3 4 
Herkogamy (mm) 
Figure 9: Herkogamy (mm) graphed against autonomous selfing rates 
(selfing rate = seed set/flower when pollinators are excluded) for thirteen 
species for which we have this data. 
3 7  
Discussion 
Mating types 
While several floral forms exist within the New Zealand taxa of Myosotis, species studied 
to date separate into one of two distinct mating types; those able to set seed themselves 
(autonomous) and those unable to set seed without a vector (non-autonomous) . These 
types can be predicted by measuring herkogamy or spatial separation between anthers 
and stigma. Those species that are 'always herkogamous', (sensu Robertson and Lloyd, 
1 99 1 ), require vectors to achieve pollination. Those that are 'initially herkogamous' or 
'never herkogamous' (sensu Robertson and Lloyd, 1 99 1 )  are able to self-pollinate 
autonomously. 
The ease by which herkogamy can be measured in the field as opposed to conducting the 
type of detailed experiments carried out in this study could be made more use of in 
determining pollination requirements for other rare Myosotis species. Simply measuring 
herkogamy in a range of flowers can determine the degree of autonomous selfing a 
particular species may experience. The population dynamics of species will be affected 
by the level of autonomous selfing operating, knowledge of which, can assist in 
predicting a populations' vulnerability to extinction. The density dependence for 
reproduction has been found to occur in all poIIinator-requiring species studied so far 
(see Chapter three) .  These species were pollen limited in low-density patches .  A small, 
thinly scattered population of a species capable of self-pollination is not necessarily a sign 
of threat, but could provide a warning for a pollinator-requiring species . 
Results for M brockiei showed there was also a significant population effect on seed set . 
This was the only species where more than one population was used to collect this data. 
In another study, data were collected on seed set by open pollinated plants fro m  several 
populations and although local density had strong effects on seed production, there was 
no popUlation size effect (see Chapter three). Two of the three sites of M. brockiei were 
on ultramafic outcrops, which were quite similar in terms of substrate and aspect, while 
the other population sampled from was on tertiary limestone in a very different habitat. 
3 8  
Self-compat ib i l ity and pol l en l im itation 
There was no significant difference in seed set by flowers receiving self- versus cross­
pollination treatments for any of the species in this study. All species of New Zealand 
Myosotis studied to date have been found to be fully self-compatible, but differ in their 
ability to set seed autonomously. Self-compatibility is thought to be the usual state for 
New Zealand genera (Godley, 1 979) although the true level of self-incompatibility in our 
flora is still not very wen known (Webb and KelIy, 1 993) .  Other genera for which self­
compatibility is the usual state are Parahebe (Garnock-Jones, 1 976), Cardamine 
(Pritchard, 1 95 7), Epilobium (Brockie, 1 95 9), Cotula (Lloyd, 1 972) Gentiana (Webb 
and Littleton, 1 987) and Peraxilla (Robertson et al. 1 999). Self-incompatibility has been 
confirmed in only a few New Zealand plants e .g. Pseudowintera, Corokia, Cordyline and 
Discaria, but it is thought that not enough is known to assess true levels of self­
incompatibility in the New Zealand flora (Webb and Kelly, 1 993) .  
For non-autonomous species, seed set by hand-pollinated flowers was found to be 
significantly higher than seed set by unmanipulated flowers. In addition, there was a 
large degree of variation in the amount of seed set by the unmanipulated flowers 
compared to those hand pollinated. Hand-pollinations show that the variation in seed set 
by these species is not due to resource limitation as flowers given hand pollination 
treatments were invariably able to average significantly more seed than that set by 
unmanipulated flowers. The variation in seed set was not due to inbreeding depression, 
as there was no significant difference between self and cross pollination in terms of seed 
set; inbreeding depression is therefore not seen at least at the level of seed set. I can 
conclude that the significant difference in seed set between hand-pollinated and 
unmanipulated flowers in non-autonomous species is due to pollen limitation. Pollen 
limitation and the resultant lower seed output can cause problems for plant populations 
when recruitment is unable to keep up with mortality. There is a widely held view 
among population biologists (e.g. Crawley, 1 990) that plant population growth is usually 
not limited by seed production but by micro site availability. Therefore lower seed output 
does not affect demography. However, Turnbull et al. (2000) have reviewed the 
literature on seed limitation studies and around half of those reviewed showed evidence 
of seed limitation .  
There i s  a possible third mating type operating in New Zealand Myosotis. A preliminary 
3 9  
study carried out on the rare, southern New Zealand endemic, M oreophila, in the 
northern Dunstan Mountains, found both pollination systems operating within the same 
plants within the population (Appendix 2). Some flowers were able to set seed 
autonomously while others required a vector to set seed. This was due to variation in 
style height. This was also observed at Mount Arthur, in a population of the Nelson 
endemic, M angustaia. In the initially herkogamous M 'lytteltonensis ' ,  the large 
variation in pistil length can result in both selfing and non-selfing phenotypes  within the 
same population (Robertson, pers. comm.) .  Further study of these taxa is required to 
determine more about this third type of syndrome in which both selfing and vector­
requiring morphologies coexist in the same population. Populations of plants with mixed 
mating systems can be at an advantage in certain circumstances. In changeable 
environments, as population size varies  and therefore possible mates, so too can 
pollinator availability such that when population size is low, selfing individuals are 
selected for (Karron, 1 99 1 ) . A positive feedback loop can establish, as seed production 
by self-pollinating individuals is generally high and constant, recruitment chances are 
improved by higher seed production that ultimately results in an increase in population 
size. At times when population size is large enough to attract pollinators, the presence 
of outcrossing phenotypes in the population can then be beneficial, particularly if 
inbreeding depression is occurring. In fact the high and consistent seed production of 
self-fertile plants could allow for considerable selection in the offspring without affecting 
demography at all (Luitjen et al. ] 998). Wright ( 1 93 9) considered such a situation to be 
advantageous to populations in which reproduction is predominantly selfing. He 
considered occasional crossing could allow for effective selection by genotypes in a 
"continuously restored field of variability" (Wright, 1 93 9) .  The mixed mating strategy 
therefore allows populations to persist in difficult circumstances and then take advantage 
of more favourable conditions when they occur. 
Habitats, d i stributions and rarity 
These results are in contrast to other studies of breeding systems in relation to the 
environment in which they live. Vector-requiring species usually have the more lowland, 
widespread distributions by comparison with their autonomous counterparts, which tend 
to have alpine and restricted distributions (e.g. Lloyd, 1 965 ;  Arroyo, 1 973 ; Garnock­
lones, 1 976; Webb and Pearson, 1 993). Selfing is expected to be more frequent in 
unpredictable environments due to pollinator p aucity and small population size (Uoyd, 
40 
1 980) .  Explanations were provided in terms of selfing (considered the derived 
condition) evolving in response to the late start or to reduced levels of insect activity 
during cold,  windy weather and the short alpine summer (Garnock-Jones, 1 976;  Webb 
and Pearson, 1 993) .  In New Zealand Myosotis however, the selfing taxa generally have 
more l owland and widespread distributions (e.g. M /orsteri), while the alpine and 
geographically restricted taxa tend to be the vector-requiring ones (e .g. M monroi). 
Species that require a vector to achieve pollination have all been found to exhibit inverse 
density-dependence for reproduction (Chapter three). These species require population 
densities at  levels that attract pollinators. It is more difficult for these taxa to establish 
new p opulations and colonise new territory. Therefore, we expect to see those species 
occurring with more geographically restricted distributions. For these species, 
individuals are more successful at reproduction when in dense patches rather than sparse 
ones. Therefore, we might expect those species to have larger, more abundant local 
poputations . This provides a mechanism by which the observed p atterns of density and 
distribution are maintained and could only maintain such patterns if seed production is 
important to the demographics of such populations (see Chapter three). If a propagule 
from an autonomous type disperses into a new area, a plant can grow, reproduce and 
colonise a new area by the germination of one seed. On the other hand, if such a 
propagule from a non-autonomous type disperses into a new area, grows, flowers and 
dies without pollination occurring it may never set seed. Therefore colonisation will not 
occur. By this means, individuals with autonomous morphologies can become more 
widespread and colonise new ground .  
Mating system evolut ion 
Within any taxon exhibiting an array of breeding systems from obligate outcrossing 
through to autogamy, the direction of evolution is generally considered to go fro m  
outcrossing t o  selfing (e.g. Arroyo, 1 973 ; Garnock-Jones, 1 976;  Barrett e t  al. 1 996). 
This implies that the ancestors of the New Zealand Myosotis taxa are or were 
outcrossing. However, most species that establish on remote islands tend to be self­
fertilizing species as such individuals can start a reproducing colony by the arrival of just 
one individual (Lloyd, 1 980; Pannell and Barrett, 1 998). S ince much of the extant flora 
of New Zealand, including Myosotis, is thought to have arrived via recent long distance 
dispersal (e .g .  Winkworth et al. 1 999), selfing is the more likely ancestral state for these 
taxa. While a large percentage of most island floras is made up of self-fertilizing taxa, 
4 1  
N ew Zealand does not follow this trend and has a high frequency of unisexuality among 
its flora (Lloyd, 1 980) .  This is thought to be due to subsequent speciation that has 
occurred into new environments with outcrossing types evolving secondarily (Lloyd, 
1 980) .  Therefore the ancestral state for New Zealand Myosotis is likely to have b een a 
self-fertilizing species. The full range of mating types observed occurs within one floral 
morphological class, i .e .  the tube (Robertson and Lloyd, 1 99 1 ). This is due to variation 
in style and filament lengths, indicating plasticity for these traits exists within the 
genomes of these taxa. Studies in the Polemoniaceae, which comprises a range of taxa 
with a variety of reproductive modes, show phylogenetic constraints do not limit 
opportunities when ecological conditions demand shifts in pollination and mating systems 
even though autogamy does tend to occur terminally in the phylogeny (Barrett et al. 
1 996) . As brush blossom floral forms are not found outside New Zealand, this floral 
form has likely evolved here. As filament length is the main feature of brush blossom 
flowers that distinguishes them from tube blossoms and plasticity for filament and style 
l ength are known, then brush b lo ssom has possibly evolved from the tube blossom type. 
The current distributions of the New Zealand species of Myosotis tend to support the 
theory that outcrossing types have evolved secondarily. The brush blossom taxa, in 
particular, have very restricted distributions. The self-fertilising species tend to have the 
widespread, lowland distributions, while the vector-requiring species tend to have more 
restricted distributions. 
42 
CHAPTER THREE 
Al lee effects i n  plant reproductive performance:  Local density, population 
size, rarity and reproductive success in  natural populations of Myosotis L. 
(8oraginaceae) 
Abstract 
Reproductive failure due to A1lee effects is a possible consequence of low population 
density and small population size. Data were collected from natural populations of five 
species of Myosotis L. (Boraginaceae) with different pollination requirements and rarity 
patterns in the Nelson region of New Zealand. Seed set per flower was measured in 
populations of varying density and size. For pollinator-requiring species, Myosotis 
monroi, M macrantha, M. laeta and M hrockiei, local population density had strong 
effects on seed set, while population size had no effect. These plants were always pollen 
limited in low-density patches. For a self-fertile species, M /orsteri, seed set was always 
high and unaffected by either local density or population size and pollen was never 
limiting. These results indicate reproductive success in poIlinator-requiring species of 
Myosotis is subject to ABee effects and these effects occur at a very local scale. This 
density-dependent process can explain how the different patterns of density and 
distribution observed are maintained for each species. These results have implications 
for the assessment and management of threatened Myosotis species in particular and rare 
plants generally. It is essential to know the pollination requirements and levels of density 
dependence for reproduction both for the assessment of threat and for determining 
management strategies for threatened plants. 
I ntroduction 
A central issue in conservation biology concerns management of populations of 
threatened species. Species with small populations are thought to have a greater chance 
of becoming extinct than those with large populations (e.g. Mace and Kershaw, 1 997). 
However, there i s  still a large amount of variation in probability of extinction predictions 
43 
(Gaston, 1 994) and there are some well documented cases of small populations 
persisting in very low numbers, for example some New Zealand birds (Craig, 1 99 1 ), 
which are at odds with the theoretical projections. Threatened plant populations are 
represented by several different types of rarity (sensu Rabinowitz, 1 98 1 ). S ome species 
are known only fro m  a single site, such as the extreme example of the New Zealand plant 
Tecamanthe speciasa, known only as a single individual in the wild, while others occur in 
typically small but widely scattered populations, such as Carex uncifalia (de Lange et al. 
1 999). 
Due to the large number of threatened plant species worldwide, their conservatio n  will 
have to be achieved largely in situ (Ell strand and Elam, 1 993) .  Determining critical 
thresholds in processes essential to population persistence, such as l evels of density 
dependence for reproduction, is an important p art of ensuring conservation efforts are 
effectively targeted and can contribute to our understanding of plant population 
dynamics. Plants make ideal study subjects to research the effects of local density and 
population size as such variables can easily be measured. 
It is important, initially, to identifY the breeding system for the assessment of threat status 
of any rare plant (Hamrick et al. 1 99 1 ) .  Plants with different breeding systems are likely 
to have different population structures, sizes and degrees of density dependence. Self­
fertile species can grow, reproduce and colonise a new area by the germination of just 
one seed. They do not require the presence of others to successfully reproduce and 
persist. Therefore a small population size of low density is not necessarily a sign that the 
population is threatened. On the other hand, self-incompatible plants or those that 
require a vector to achieve pollination need local population densities at levels that 
ensure a supply of cross pollen and/or attract vectors. Population d ensity and 
outcrossing rates are likely to be positively correlated (Karron et al. 1 995) .  Therefore, 
to be successful, they probably need population sizes considerably larger and denser than 
selfing species. 
The generally accepted, textbook theory on density dependence maintains that there is an 
upper density limit (the carrying capacity) above which population growth is adversely 
affected by over-crowding, competition and/or increased predation (e.g .  Begon and 
Mortimer, 1 986) .  What happens at lower than optimal densities, however, is not well 
understood and the various models in current u sage show a variety of possible outcomes 
44 
as density decreases (Kunin, 1 997a). In his review on density dependence in insect-plant 
interactions, Kunin ( l 997a) stresses the importance of understanding the behaviour of 
populations at low densities to enable us to focus our conservatio n  efforts productively 
on appropriate management techniques. 
Levels of density dependence will vary with the pollination requirements of species. For 
animal pollinated plants reproductive success is likely to depend on density and 
population size. For populations of these species, plants growing at Iow local density are 
more likely than those growing at high density to be pollen-limited in their reproductive 
success (Kunin 1 992, 1 993) .  These species may find it difficult to colonise new ground 
and therefore be  less likely to be found in small populations. Small, isolated populations 
would be less likely to persist if unable to attract pollinators. This inverse density­
dependent process, which is also known as the ' Allee effect' (Allee, 1 95 1 )  occurs where 
rates of reproduction decrease disproportionately in response to decreasing population 
density or size. Several researchers have studied Allee effects on reproductive success 
from natural populations (e.g. Silander, 1 978 ;  Kunin, 1 992), experimental populations 
(e.g. Feinsinger et al. 1 99 1 ;  Groom, 1 998 ;  Kunin, 1 993) and theoretically (e .g .  Dennis, 
1 989; Kunin and Iwasa, 1 996; Amarasekare, 1 998) .  Generally, for self-incompatible 
plants, reproductive success decreases as local population density decreases. Population 
size, which is often correlated with and sometimes not differentiated from local density 
(Gaston, 1 994), would be expected to also have a similar effect o n  reproductive success .  
S everal studies have found such population size effects on fruit and seed set when 
comparing small to large populations (e.g .  Aizen and Feinsinger, 1 994; Agren, 1 996) .  
However, there are also several studies that have found population size had no effect on 
reproduction (Van Treuren et al. 1 993 ; Kunin, 1 997b; Molano-Flores et al. 1 999) .  
When 10caJ density and population size have been differentiated, results have shown very 
different effects on species interactions and population dynamics (Van Treuren et al. 
1 993 ; Kunin, 1 997b; Molano-Flores and Hendrix, 1 999) . Yet the concept that small 
populations face increased extinction risk is an integral component of threat assessment 
and conservation management. Understanding small population dynamics is crucial in 
our effort to conserve at risk poputations. 
I examined the effects of population density and size on seed set by flowers of five 
species of Myosotis (L. )  (Boraginaceae) . All are short-lived, fully self-compatible, more­
or-less rare herbs endemic to New Zealand. For these species I wanted to test the 
45 
hypotheses that the variation in seed set found in natural populations could be due to 
local density and population size. 
Material and Methods 
Study taxa 
Myosotis L. (forget-me-nots) is a cosmopolitan genus of the B oraginaceae and has a 
worldwide temperate distribution. New Zealand is the S outhern Hemisphere centre of 
diversity for the austral group of the genus (Grau and Schwab, 1 982 ;  Winkworth et al. 
1 999) . In addition to the New Zealand taxa, the austral group contains four other 
species; two in Australia, one in S outh America and one in New Guinea. Within New 
Zealand there are 43 named species and varieties (Allan, 1 96 1 )  but an additional 25 tag 
named entities exist (Druce, 1 993) and the genus requires revision. The New Zealand 
species in the genus display a wide variety of rarity types with about 3 3 %  (including tag­
named taxa) considered threatened in some way (de Lange et al. 1 999). This h as 
contributed to the taxonomic difficulties as they are rarely encountered in the field and 
are simply not that well known. 
Within the N ew Zealand species, several different abundance and distribution patterns 
are evident . Many Myosotis species are rare and local, often occurring in single, isolated 
populations, sometimes in large numbers while others are widespread but never common 
where they occur. This provides an opportunity to study local abundance and 
distribution patterns or rarity patterns within a single genus. For example Myosotis 
forsteri i s  found within about three quarters of New Zealand' s  land area south of latitude 
3 8° S (Allan, 1 96 1 ) . While having a widespread distribution, it i s  often found as  a single 
individual or as two or three plants in a population and has been seen occasionally in 
populations as large as 30 individuals .  Although sparsely distributed, it is not considered 
threatened in any way. By contrast, M. monroi, an ultramafic endemic to mountains east 
of Nelson, New Zealand, occurs in a very restricted area. Although confined to a very 
small range size, it i s  locally common where it occurs and is usually found in relatively 
large populations of more than 5 00 individuals .  
The range of rarity types i s  quite well covered by the genus as are a variety of threat 
classifications. Of the five species in this study two are classified as threatened in some 
46 
way. M laeta i s  classified as Vulnerable (Cameron et al. 1 995) and Range Restricted 
(de Lange et al. 1 999); M. brockiei is classified as Rare (Cameron et al. 1 995), I 
(Insufficiently known) (Dopson et al. 1 999) and Range Restricted (de Lange et al. 
1 999); M monroi, M. forsteri and M. macrantha are not considered threatened. 
Flowers are hermaphroditic, carried on scorpioid cymes and each is able to produce up 
to four nutlets .  Species have been found to have different mating types that depend on 
the length of the style in  relation to the position of the anthers and length of the filaments 
(Robertson and Lloyd, 1 99 1 ) . M oore (in Allan, 1 96 1 )  states that " . . .  exserted anthers are 
little known in the genus outside (New Zealand)" .  I have studied several aspects of the 
reproductive biology of selected taxa. All species studied to date have been found to b e  
fully self-compatible, but differ in their ability t o  set seed autonomously (Robertson, 
1 989; Chapter two). While several floral morphologies exist within the genus, the 
species studied to date separate into one of two distinct mating types; those able to set 
seed themselves (autogamous) and those unable to set seed without a vector (non­
autogamous) . These types can be distinguished by measuring herkogamy (the spatial 
separation between anthers and stigma) (Robertson and Lloyd, 1 99 1 ). In the wild in the 
pollinator-requiring species, seed set by unmanipulated flowers is usually quite variable  
(Chapter two). 
F or this study I have concentrated on five species with a variety of abundance and 
distribution types and both mating types (Table 1 ) .  All species are endemic t o  N ew 
Z ealand. Myosotis forsteri, the only autogamous species in the study, i s  widely 
distributed and is everywhere sparse. The other four species are non-autogamous and 
cannot set seed when pollinators are excluded (Chapter two) .  M macrantha occurs 
throughout the S outh Island (42 - 46 S) .  Although particular with respect to aspect 
and habitat, it is usually locally common where it occurs .  M monroi is found on an 
ultramafic mineral belt that extends from D'Urville Island in the north to the Red Hills 
ridge in the south (40. 8  - 4 l . 5  0 S) .  Although range restricted it is very common where it 
o ccurs on the weathered, treeless fellfield of the mineral belt. M. laeta is known from 
two locations within the same mineral belt, at the southern end on the Red Hills Plateau 
where it is very common and on the lower flanks of Mt Starveall where known 
populations are much smaller. This species was studied at one site only. M brockiei 
u sually occurs in small populations and is found in a very restricted area geographically, 
centred in the Cobb Valley, Nelson ( 1 4  km2 at about 4 1  0 south). It is a basicole as it 
47 
occurs o n  both ultramafic outcrops as well as on limestone. 
Table 1: Summary table of the species distributions, typical abundance, herkogamy and mating type 
Species 
Jvfyosotis forsteri 
M. macrantha 
A1. monroi 
M. laeta 
M. hrockiei 
Range size 
Widespread 
South Island 
Restricted (Bryant 
Ecological District 
Restricted (Bryant 
Ecological District) 
Restricted (Cobb 
Valley -Mount Arthur 
Tablelands) 
Population Herkogamy Pollination type 
sizes 
1 -3 8  0 Autogamous 
9 - 1 000 3 . 6  mm Non-autogamous 
22-2000 1 . 8  mm Non-autogamous 
24-2000 1 .4 mm Non-autogamous 
3 -90 3 . 2  mm Non-autogamous 
Data on abundance were gathered from 1 997- 1 999. Distribution were obtained from the 
most recent treatment in A1lan ( 1 96 1 )  and from herbaria records (CHR2, WELT:" 
WEL TU4 and AK5). These are summarised in Table 1 .  
Local density and populat ion size effects on seed set - sampl ing procedure 
S eed set counts were made for plants growing in a range of densities and population 
sizes. The number of seed set by each flower was made as a count (0 4), and then 
converted to a proportion of ovules set by each plant. Local density was measured as 
number of inflorescences in a three-meter radius around the focal plant for which seed 
set counts were made. Population or patch size was counted as number of adults 
(flowering plants) in the population or patch. 
2 CHR: 
3 WELT: 
4 WELTU: 
5 AK: 
Landcare Research Herbarium, Lincoln 
National Museum Herbarium 
Victoria University of Wellington Herbarium 
Auckland Museum Herbarium 
48 
Pol len l im itation experiment 
Areas where Myosotis plants are less dense might be less suitable for the species  than 
more densely populated areas and plants could be setting less seed for that reason. To 
check this, pollen supplementation was carried out on flowers of plants in a 
representative range of densities to discriminate between resource and pollen limitation. 
Pollen from neighbouring plants was applied by hand to stigmas. Control flowers were 
left unsupplemented on the same plant. The resultant seed set was compared . 
Data analysis 
Three analyses were carried out. The seed set data gathered were converted into a 
proportion (of the total possible) and arcsine square root transformed. Firstly, the 
proportions of seed set by unmanipulated flowers were fitted against local flower density, 
using a Generalised Linear Model (GLM). Secondly, the same analysis was carried out 
on the seed set by flowers that had been hand pollinated, which were also fitted against 
local flower density. Thirdly, to test for population size effects, the least squared means 
obtained from the first analysis for each population were then correlated against 
population size, using a GLM. 
These analyses were all performed using S-PLUS version 4 .5  (MathSoft Inc. 1 998) .  
Results 
Myosotis brockiei, Myosotis macrantha, Myosotis monroi and Myosotis laeta 
Local density had strong effects on seed set in  natural conditions in  all four species and 
there were popUlation effects for all species with more than one study population (Fig. 1 ,  
Table 2) . M. laeta was studied at just one p opulation so population size effects could 
not be tested for. Populations varied significantly, but the variation was not due to 
population size. When means for each population were adjusted for local density the 
population effect disappeared (Fig. 2, Table 3 ) .  Local density had no effect on seed set 
by pollen-supplemented flowers (Fig. I ,  Table 2). Two of the species, M macrantha 
and M. laeta, had low seed set results by some of the pollen-supplemented flowers at 
low flower density sites (Fig. 1 ) .  
49 
1 . 0  
0.8 
§ 
t:' 8. 0.6 
o 
e; 
� 0 4  
(/) 
0.2 
0 0  
1 . 0  
0 .8  
� 
� 0.6 -
S 
� 0 .4 ] UJ 
0.2 
0 0  
1 .0 
0 .8 
0 0  
Myosotls forsten 
0.0 0.2 0.4 0.6 
Inflorescences m�2 
• • - • 
() • 0 (I • -
0° o 
0 (I 
(I 
0·· () 
• 
0 
• Myosotis macrantha 
0 0  0 .2  0 4  0 .6  
Inflorescences m-2 
• • • • 
(�) 1..0 • I 
8 
o 
() . 0  
0 0  0.5 1 . 0  1 . 5  
Inflorescences m-2 
0.8 1 0  
• 
o 
Myosotis laeta 
2.0 
1 .
. 
, ! 0 8 - • 
0 
0 
() 
0 0  
0 0  
1 . 0  
0. 8 
0 .2 
0 0  (I 
0 .0  
• • 
••  0 
0 
0 o 
o 
o Myosotis brockiei 
0 .2 0 .4  0 .6  0 .8  
Inflorescences m"2 
0.2 
• 
--0-
0.4 0.6 
Supplementary 
Unmanipulated 
Fib'llrC 1: Local flower density effects on seed set by unmanipulated flowers and pollen 
supplemented flowers graphed for each species M jorsteri, M brockiei and M. laeta had 
linear curves fitted. M. macrantha had a log] n curve fitted. M. monroi had a polynomial 
curve fitted. Each data point represents the mean seed set for each plant. All supplementation 
flowers had paired unmanipulated flowers seed production recorded. Lines are fitted to the 
unmanipulated points. See Table 2 for details of the statistics. 
5 0  
0.05 
� 0.00 
� 
D 
� � -0.05 
� 
-0 .10  
-0 . 15  
0 .4  
� 0.3 
E 
D � 0 .2  
is' ..: 
0 . 1  
0 .0  
• 
• 
• 
• 
• 
Myosotis forsteri 
1 0  1 5  20  
Population size 
• 
• 
--
-� 
�------------
.. // 
// 
• 
• 
• Myosotis macrantha 
40 80 120  
Population size 
0.5 
0 .4  
• '" c 
� 0.3 • il ; • � 02  • 
0 . 1  
0 .0  
1 0  2 0  30 40 
Population size 
0.2 • 
• 
0.1 
'" 
c '" 
� • 
D " 0 .0  • ; is' ..: 
-0.1 
-0 2 
160 200 400 600 800 1000 
Population size 
Figure 2: The relationship between population size and seed set by flowers on unmanipulated 
plants using means from each population. Means are adjusted for local density. None of these 
relationships were significant. 
Myosotis forsteri 
Local density had no effect on seed set in natural conditions and there was no population 
effect (Fig 1 ,  Table 2) . When means for each population are adjusted for local density 
there was no population effect (Fig. 2, Table 3) .  Local density had no effect on seed set 
by pollen-supplemented flowers (Fig. 1 ,  Table 2) .  
5 1  
Table 2: Density effects on seed set in natural conditions and with pollen supplementation of flowers 
��---
. SI!ecies Factor Df F value P % eXI!iained 
Myosotisforsteri Population 6 0 .5353  0.7758 1 2.23 
Natural conditions 
Flower density 0 .0361  0 .8509 0 . 1 4  
Residuals 23  0 .05 14  
Pollen supplementation Flower density 1 0 .929 0 . 3897 1 8.85 
4 
Myosotis brockiei Population 6 2 .2827 0 .07 9 1  29 .5 1 
Natural conditions 
Flower density 1 3 .7 1 49 0 .00 1 5  29 .55 
Residuals 1 9  
Pollen supplementation Population 2 17 .65 1 55 0 .0536 94.46 
Flower density 3 .07 1 35 0 . 8 144 0 . 1 9  
Residuals 2 
111yosotis macrantha Population 6 2. 2748 0 .0736  26.43 
Natural conditions 
(log} o)flower density 1 5 . 98 17  0 .0006 30 .96 
Residuals 22 
Pollen supplementation Population 3 UJ76833  0 . 3907 1 5 . 9 1  
Flower density (logl O) Cl.cn 43Cl2 0 . 1 0 1 4  1 5 . 1 4  
Residuals 14  
lvfyoso/is monroi Population 4 3 . 1 2735 0 .0253  1 3 . 8 1  
Natural conditions 
Polynomial (flower 2 1 9 . 53660 0 .0000 43 . 1 4  
density, 2 )  
Residuals 39  
Pollen supplementation Population 1 3 . 3058 0 ' ()827 1 2.53 
Flower density (logI0) Ul723 0 . 3 1 l7 4 .06 
Residuals 22 
Myosotis laeta Flower density 1 10.7457 0 .0034 32 .82 
Natural conditions 
Residllals 22 
Pollen supplementation Flower density 0.074446 0.7880749 0 .42 
6 
Residllals 1 8  
Table 3 :  Population size effects after local density i s  adjusted for. 
... �I!��.�!-:.� ..... . ... . ................ . . .... . .. 1!:1l.c.t.().r. . . ...... . . ....... . ... . ....... . .... ...... �f. . .... ... � . .Y.�!�� ........ � ................... . �!?.!-:.�p.!.��.�.'::� . . . 
Myosotisforsteri Population size 1 0 . 3002 0 .6073 5 .68 
Residuals 5 
Myosotis brockiei LoglO Population size 1 0 .2922 0 .6 1 20 5 .74 
Residuals 5 
Myosotis macrantha LoglO Population size 
Residuals 
lVfyoso/is monroi Log10 Population size 
Residuals 
5 
1 
3 
3 . l 783 
1 . 1 83 
0 . 1 3 47 3 8.84 
0 . 3563  28.22 
52 
Discussion 
These results demonstrate that knowledge of breeding system is  important in  
conservation risk assessment of plants. Here, I have shown a selfing species  is not 
threatened with recruitment restriction when found in small populations. In the selfing 
species, Myosotis forsteri, local density had no effect on seed set, there was no density 
effect of pollen supplementation on seed set and there were no population size effects. 
These results are not surprising. For self-compatible, autonomous species, small 
population size is not a sign of threat on its own. The need for large, dense populations 
to  get adequately pollinated is not there for those that are able to self-pollinate. 
For those species that required pollinators, however, the local flowering plant density 
had a large impact on seed set. There are three possible  reasons why low local density 
could have such an impact on reproductive success. Firstly, the quality of pollen 
deposited on their stigmas may be poorer in low-density patches. There may be more 
geitonogamous (within-plant) pollen transfers or movement between closely related 
individuals at low plant densities, thus low seed set by these plants may be indicative of 
inbreeding depression (Bosch and Waser, 1 999) . However, all species in this study have 
b een found to be fully self-compatible and there is no significant difference in seed set by 
hand self- and cross-pollinations (Chapter two) .  Inbreeding depression, therefore, does 
not appear to be operating at the level of seed set at least. 
S econdly, local plant densities may be influenced by the local site conditions within each 
population .  Availability of resources such as soil moisture, nutrients and solar radiation 
levels can influence germinatio n  and growth of new plants (Bosch and Was er, 1 999) as 
well as limiting the number of ovules that can develop into seed even if flowers are well 
p ollinated. However, I found no density effects in the autonomous species, Myosotis 
forsteri, and, therefore no evidence that local conditions affect seed set in that species. 
In general, population effects on seed set, if they occur at all, are small. If resource 
availability is an important limiting factor, I would expect some population effects as 
some populations will be in more suitable places than others. In the pollinator-requiring 
species, density had no effect o n  seed set in flowers that received supplemental pollen 
suggesting that plants were pollen limited rather than resource limited in low density 
p atches. 
5 3  
Thirdly, it could be that lower levels of pollen are being deposited on stigmas in low­
density sites and that this causes an impact on seed production. As I have eliminated the 
other two causes, I conclude that it is the quantity of pollen receipt, which is limiting 
seed production at low plant densities in the four pollinator-requiring species studied. 
F or the two species M manrai and M macrantha, in some p opulatio ns local flower 
densities reach high levels, such that pollen limitation is eliminated. For M manrol, a 
quadratic curve provides a better fit of the data, and optimal densities are intermediate. 
These optimal levels do not appear to be reached in either M. laeta or M brockiei .  
There may be resource limitation from intraspecific competition affecting seed 
production in M monroi at those higher flower densities. 
F or the two species M. monroi and M laeta, some of the hand-pollinated flowers set low 
seed levels at low density sites, although it was not significant in the analysis. This could 
be due to the lower density sites containing more closely related individuals with poorer 
quality pollen. 
Although there were no detailed, systematic pollinator observations to accompany these 
data, by eliminating other possible mechanisms for poorer seed set by low density plants, 
inferences can be made regarding pollinator behaviour to explain how pollen receipt is 
limiting seed production. Visitors to plants growing at low density are expected to be 
fewer and less flower constant than visitors to plants in high-density patches (Kunin and 
Iwasa, 1 996). Kunin ( 1 997b) and Groom ( 1 998) found plants growing at low densities 
had fewer visits by pollinators than individuals growing at high densities. Rare, self­
compatible plants are often pollinated by generalists. Therefore visitors to less dense 
plants may be carrying pollen from other species (Groom, 1 998) .  Kunin ( 1 997b) found 
pollinators visiting sparse plants were less flower-constant, and are therefore are likely to 
carry a higher percentage of inappropriate pollen to plants of low density. 
In this study, the size of the population had no effect on seed set (though I have less 
statistical power to detect population size effects as only a few populations of each 
species were sampled) . Three species, Myosotis brockiei, M. macrantha and M. monroi 
show population differences in seed set in their original ANOV As. However, there is no 
significant correlation between population size and seed set once the means are adjusted 
for local density. While the very smallest populations of these species have the lowest 
values for adjusted seed set, the reproductive output of the other populations does not 
5 4  
appear to be influenced by population size. Although insufficient populations were 
studied, it is possible that there may be a minimum size necessary to attract sufficient 
pollinator service. 
For these pollinator-requiring taxa then, low local density is a potential problem. Low 
reproductive success can create difficulties in establishing new populations and limit 
successful colonisations (Groom, 1 998) thereby impacting on members of established 
populations. Species that have been found to suffer Allee effects in small p opulations 
tend to have bimodal patch occupancy patterns (i . e. either full or empty) . This suggests 
there is an extinction threshold at low habitat occupancy (Amarasekare, 1 998),  and may 
explain the pattern of abundance and distributions of Myosotis species seen in the field .  
So  while there were no population size effects detected in  this study, the density 
dependence of reproduction is likely to influence both the population structure and the 
size of existing populations, while eliminating those populations that are too small to 
attract pollinators. 
The positive relationship between local density and/or population sIze and plant 
fecundity, which has now been found in several other studies (e.g .  Kunin, 1 992, 1 997b; 
Lamont et al. 1 993 ,  Agren, 1 996; Groom, 1 998), is likely to affect the p opulation 
dynamics of these species. The demographic effects seen, at least in this study, are 
explained if low seed production in low-density patches is limiting population growth and 
causing local extinction at those sites. It explains why the populations of the pollinator­
requiring species are usually denser and larger than those of the selfing species. It is 
expected that population density and geographic range would vary over time. However 
there is growing evidence across several taxonomic groups, suggesting range and 
abundance are persistent species characteristics (Lawton, 1 993) .  Density and range are 
considered linked to the species fundamental niche breadth, an evolved species 
characteristic (Brown, 1 984) . These results are consistent with this body of thought, as 
the pollination ecology of each species, an evolved trait, shapes the type of population 
structure that is successful for each species . 
There is a widely held view among population biologists that plant population growth is 
often not limited by seed production. Crawley ( 1 990) concluded that plant population 
growth is more often limited by micro site availability than by seed production. Some 
pollination b iologists, such as Bawa and B each ( 1 9 8 1 ), believe plant reproductive 
5 5  
success i s  rarely limited by pollination events (Kunin, 1 992) . Seed-limited recruitment 
has very rarely been studied, (but see Eriksson and Ehrlen, 1 992; Maze and Bond, 1 996) 
but it is  thought that the persistence of plant populations will depend on the growth form 
of the species (e .g .  longevity) and on the habitat type that it occupies (Crawley, 1 990) .  
A recent review of seed limitation studies found 50% of augmentation studies and 5 3 %  
of introduction studies showed evidence o f  seed limitation (Tumbull e t  al. 2000) . My 
study was conducted on short-lived herbaceous rare plants that occur in a range of 
different population types. Generally species with density-dependent reproduction tend 
to have clumped distributions while those that do not have d ensity-dependent 
reproduction occur in sparse, small populations. The pollinator - plant interactions for 
the vector-requiring species of A1yosotis shown with this data set are very sensitive. 
Loss of this interaction will lead possibly lead to loss of plant populations over time. At 
low densities, it may be hard to attract and ultimately maintain p ollinator populations. 
Eventually these plants may die and if they've only rarely set seed it is hard to imagine 
how populations can persist in the long term under these circumstances. 
An important means by which these high densities may be maintained is through selection 
against over-dispersal (Kunin, 1 992) . Kunin ( 1 992) introduced the concept that density­
dependent fertilization may select against over-dispersaL Mechanisms that improve 
dispersal ability are usually viewed as positive attributes to a species as the ability to 
disperse into otherwise unoccupied sites has the potential to increase fitness and will 
therefore be favoured by selection (e.g .  Webb, 1 998). However, such dispersal events 
will be unsuccessful for many species particularly those that are restricted to particular, 
insular habitats or those that are not self-fertile. Cody and Overton ( 1 996) found 
evidence for reduced dispersal potential within just a few generations in island plant 
populations of weedy, short-lived, wind-dispersed plants when compared to mainland 
populations. In this system such evolution could involve an increase in seed size. This 
idea is  investigated further with respect to all New Zealand species (see Chapter five). 
These results are consistent with the research carried out to date which, with a few 
exceptions, are generally showing low density plant populations have reduced pollination 
success (Kunin, 1 997b). These exceptions are generally from studies of self-compatible 
species (e.g .  Klinkhamer and de long, 1 990; Molano-Flores et al. 1 999), so this study is 
one of a growing number of studies finding these effects in fully self-compatible 
xenogamous (vector-requiring) species (e.g. Fritz and Nilsson, 1 994; Groom, 1 998) .  
5 6  
These results also have implications for studies of the evolution of floral form, some of 
which have focused on pollinator-mediated selection on floral traits .  Typically these 
studies make phenotypic measurements of floral characters, such as coroUa size, which 
are then compared to seed or fruit set and are explained in terms of pollinator visitation 
rates to determine the effect of floral morphology on female fitness (e.g. Galen, 1 996). 
There i s  a large amount of variation in seed set in natural populations some of which I 
have found is due to local density. I found that about 3 0% of the variation in seed set is 
explained by local flower density in the four vector-requiring species (range 29. 5 5  -
43 . I )  (Table 2). It may be useful in future studies to include local density, which is  very 
easy to measure, as a variable to account for any density effects that would otherwise be 
p erceived as unexplained noise and thus improve the chance of detecting phenotypic 
effects on seed set. 
57 
CHAPTER FOUR 
Precocious bud pol l ination :  Maximizing chances for cross poll i nation in  
the ultramafic endemic Myosotis monroi Cheesm. (Boraginaceae). 
Abstract 
Precocious stigma presentation was investigated In the geographically restricted, 
serpentine endemic forget-me-not Myosotis monroi. Stigmas collected from precocious 
buds, in which the style and stigma protrude out of the bud before the p etals open, 
showed some pollination was taking place at the precocious phase. 26 .2  % of the 
precocious stigmas collected had received pollen, and 1 1 . 9 % had received at least 5 
pollen grains. This contrasts with stigmas collected from flowers at the end of the male 
phase, where 8 8 . 1 % had received pollen, 75 . 8 1  % with at least 5 pollen grains. Hand 
pollinations confirmed precocious stigmas were receptive but seed set by hand-pollinated 
open flowers was significantly higher. Stylar precocity in M. monroi effectively 
lengthens the female phase of this protogynous species. M. monroi also shows far 
greater phenological synchrony of within plant flowering than five other species of New 
Zealand Myosotis and this results in a much larger flowering display. Large floral 
displays, while attracting pollinators, have the disadvantage of increasing chances for 
geitonogamous pollinations. It is hypothesized that the impact of a large floral display 
on levels of self-pollination in M. monroi is alleviated to some degree by the relatively 
long, initial female-only phase. 
I ntroduction 
Floral traits that influence outcrossing rates, such as the separation of female and male 
functions, are common in angiosperms (Faegri and van der Pijl , 1 979). For individual 
hermaphrodite flowers, the separation of pollen and stigma presentation in time 
( dichogamy) and space (herkogamy), are traits that have evolved to avoid interference 
b etween these two functions, which have the additional utility of improving outcrossing 
potential (Webb and Lloyd, 1 986) .  Although treated as separate functions by Webb and 
5 8  
Lloyd ( 1 986) and Lloyd and Webb ( 1 986), these mechanisms (herkogamy and 
dichogamy) can occur together in many different flower types (Luijten et al. 1 999; 
Robertson and Lloyd, 1 99 1 ) . For self-compatible plants, the herkogamy and dichogamy 
exhibited by flowers are the main means by which chances for cross pollination events 
can be influenced. Factors that increase pollen carryover or cause pollinators to make 
more frequent interplant movements are also potentially important. The degree of 
synchrony within the plant and the degree to which it is complete within a flower are two 
aspects of dichogamy that Lloyd and Webb ( 1 986) recognized as important to the 
breeding system. In biotically pollinated flowers, protandry (the presentation of stigma 
after the pollen) is more common than protogyny (the presentation of pollen before the 
stigma) (Lloyd and Webb, 1 986) although it is thought that protogyny gives better 
protection against self-pollination (Robertson and Lloyd, 1 99 1 ) .  The particular set of 
dichogamous and herkogamous traits that occur in a self-compatible species will 
influence levels of self-pollination. Webb and Lloyd ( 1 986) described three main classes 
of herkogamy found in angiosperms: interfloral (i. e .  monoecism); reciprocal (i . e. 
heterostyly) and homomorphic, in which flowers are hermaphroditic, of one form and 
pollinator contact is unordered or ordered. In ordered herkogamy, pollen and stigma 
presentation relates to the pathway of the reward-seeking pollinator (Webb and Lloyd, 
1 986). Approach herkogamy, a type of ordered herkogamy, occurs when the stigma 
protrudes beyond the anthers and is usually contacted first, which decreases the 
likelihood of self-pollination (Robertson and Lloyd, 1 99 1 ) .  
In species that require a vector for pollination to  occur, self and cross pollen alike must 
be deposited via the vector (Holsinger, 1 996), so the longer the stigma is expo sed prior 
to anther dehiscence, the greater the chance of outcrossing. Pollination studies carried 
out previously on the New Zealand endemic Myosotis coiensoi, a pollinator-requiring 
species that has a large floral display, found flowers were protogynous and will usually 
have been adequately pollinated prior to anther dehiscence when weather conditions are 
good (Robertson, 1 992). However, Robertson ( 1 992) estimated as many as 5 0% 
pollinations were geitonogamous. M colensoi flowers spend an initial 1 2 . 1  % of the time 
open in the female phase prior to anther dehiscence (Robertson and Lloyd, 1 99 1 ). 
A review of the literature has revealed that stylar precocity has generally been assumed 
to indicate protogyny (e.g .  Solbrig and Cantino, 1 975) .  Hoc et al. ( 1 994) investigated 
the assumption in four Prosopis species (Mimosaceae) and found that precocious styles 
5 9  
did  not indicate protogyny and that stigmas were not receptive until  after anthesis and 
anther dehiscence had begun. The Hoc et al. ( 1 994) is the only study of  thi s  type that 
has been carried out. Precocious styles and their  stigmas have never been proved to be 
receptive during the precocious phase or even prior to anthesis. 
Myosotis monroi has brush blossom floral morphology (Robertson, 1 989;  Chapter two) 
(Fig. 1 ) . Flowers exhibit approach herkogamy, as the stigma protrudes further than the 
anthers. The stigma presentat ion in the buds is often precocious, potentially exposing 
the stigma for pol l ination before the bud opens (Fig. 1 ,  lower insert) .  It has been 
suggested stigmatic precocity in this species has the effect of extending the length of the 
female phase (Robertson, 1 989). 
Selfing rates and levels of  dichogamy can be compared to determine whether mating 
system evolution is influenced by sel fing rates. High levels of selfing may be expected 
to be accompanied by low levels of dichogamy. 
The aims of this chapter are to find out if pol l ination occurs at the precocious stage, i f  
so, how much, and how the precocious phase affects the t ime spent i n  the female phase 
in comparison to related Myosotis species that do not have precocious buds. 
Figure 1: Myosotis monroi. Dun Mountain. Photos (main and top insert) Alastair Robertson, (lower 
insert) Bill Malcolm. 
60 
Materia l  and Methods 
Myosotis monroi has a restricted, disjunct distribution that is confined to an ultramafic 
mineral belt that lies east of Nelson, New Zealand. All fieldwork for this study was 
conducted at Dun Mountain (Fig. 2). A previous study has found that M monroi is fully 
self-co mpatible, but requires a pollinator to achieve pollination (Chapter two) . 
Stigmas were collected as pairs from 42 plants - one a precocious bud and another fro m  
a n  open flower at the end o f  the male phase on the same inflorescence. Collections were 
made at the end of the day. Stigmas were then mounted on slides in fuchsin gel for later 
viewing and sconng. Stigmas were scored for pollen load using a compound 
mIcroscope. 
1 00 km 
Figure 2: Known distribution of Myosotis monroi, Nelson 
region, South Island, New Zealand. 
6 1  
2 1  plants were caged to exclude polIinators while inflorescences were in closed bud. As 
stigmas protruded from the bud and as flowers opened, hand pol linations were carried 
out. Precocious buds and open flowers on the same inflorescence were hand pollinated 
to determine whether the stigma was receptive at the precocious phase. Cages were then 
replaced to avoid any natural p ollination occurring after treatments were carried out. 
Three weeks after treatment, seed set was counted. The developing seeds were easily 
observed in maturing calyces. 
Phenological data were collected on M monroi. 'Static' samples were made to estimate 
the relative time a flower spends in each sexual stage (sensu Robertson and Lloyd, 
1 99 1 ) . Static samples are made by recording the sexual stage each flower is at within 
each inflorescence. If the stigma is protruding from the closed bud, or the corolla is 
open but none of the anthers have begun dehiscence, then the flower is recorded as in the 
female phase. When anthers b egin to dehisce, flowers are then recorded in the male 
phase.  When all five anthers have dehisced, and pollen is no longer visible, flowers are 
recorded in the post pollination phase. From these data percentages of flowers at each 
stage were determined so that the level of within-plant synchrony could be measured and 
the level of dichogamy could be determined. 'Static' samples were taken of several 
species of Myosotis for comparison. Species were chosen to represent the full range of 
floral syndromes found in New Zealand Myosotis. Samples were made during peak 
flowering times for all species. 
Data Analysis 
The seed set data was converted into a proportion of seed set per flower then 
transformed with an arc-sine square-root transformation. All analyses were performed 
u sing S-PLU5� version 4 . 5 .  A one-way ANOVA on the transformed proportion of seed 
set by flowers pollinated at precocious and fully open stages, was performed. These data 
are presented as box plots. A poisson analysis of variance was carried out on the number 
of flowers open per plant, the number of female phase flowers, and the number of 
inflorescences per plant A gaussian analysis of variance was p erformed on the average 
number of flowers per inflorescence. A binomial analysis of variance was carried out on 
the proportion of female flowers per inflorescence. Box plots are drawn to examine the 
data. Following these analyses, a posteriori Tukey tests were used to compare the 
62 
means of each species . 
The mean proportions of flowers in each phase, female, male and post-pollination, were 
determined and expressed as percentages of the total. 
Results 
Receptivity of precocious buds 
1 .0 
0 8  
c:-o 
i 2 06 
8; 
a:; <f) 
u 
� 04 
if) 
0 2  
a 
o.o ·'----------r------,------L · 
Fully op"n fi<Mers Precocious buds 
Figure 3: Boxplot of resultant seed set from the pollination treatments carried out at the two phases. 
Flowers pollinated during the precocious phase set seed, but there was a significant 
difference between that and seed set by fully open flowers (p=O.0049; Fig. 3 ,  Table 1 ). 
There was no plant effect (p=0.4266, Table 1 ) .  Seed set by flowers hand pollinated in 
the precocious phase averaged 2 .7  seeds per flower, while seed set by flowers hand 
pollinated at the fully open phase averaged 3 , 5  seeds per flower (Appendix 3 ) .  
Table 1 : ANOVA results comparing seed set by hand pollinated precocious buds and fully open flowers 
Factor df SS MS F Value P 
Plant 0.0884 0,0884 0.6454 0.4266 
Fully open flowers or 1 .22 1 3  1 .22 1 3  8 , 9 188  0 .0049 
precocious buds 
Residua1s 39  5 . 3404 0. 1 37 
63 
Pol /en /oad 
26. 1 9% of the precocious stigmas collected had received pollen, and 1 1 . 9 % had 
received at least 5 pollen grains. 88 . 1 % of the fully open flowers stigmas had received 
pollen, 75 . 8 1  % had received at least 5 pollen grains. Therefore some p ollination does 
occur in natural conditions at the precocious bud stage (raw data in Appendix 4). 
Phenology 
The number of inflorescences per plant varied significantly among the six species (Table 
2) .  M. monroi and M macrantha had on average more inflorescences per plant than the 
other species, and significantly more than M brockiei, M. laeta and M tenericaulis (Fig 
4) . 
1 0  
....... c 
re 8 CL 
I-
(J) CL 
(/) 6 (J) () c (J) () (/) 4 (J) l-
Q 4= C 
2 
0 
ab be 
ab 
d cd 
M. brockiei M. /aeta M. monroi 
a 
M. forsteri M. macrantha M. tenericaulis 
Fig 4: Box plots of the number of inflorescences per plant. Species that share letters above the boxes 
are not significantly different. 
64 
Table 2: Analysis of the number of inflorescences per plaut 
Model Df 
Null 
Species 5 
Deviance 
40. 8 9  
Residual Residual 
df deviance 
1 1 9 
1 1 4 
100. 3 6  
5 9. 47 
F value 
1 4. 00 
P (chi) 
< 0. 0000 1 
The number of flowers open per inflorescence also varied significantly among the six 
species (Table 3) .  M. monroi and M. laeta had the highest average number of open 
flowers per inflorescence, and significantly more than M forsteri (Fig. 5) .  
(]) t) c 
(]) 
1 0  
hl 8 
� 
o q:: c 6 -
L-
(]) 0-
� 
(]) 
� o q:: 
c 
(]) 
0-
o 
2 
o 
b 
b 
ab 
ab 
ab 
a 
M. brockiei M. laeta M. monroi 
M. forsteri M. macrantha M. tenericaulis 
Figure 5 :  Box plots of the number of flowers open per inflorescence. Species that share letters above 
the boxes are not significantly different. 
Table 3: Analysis of the number of flowers open per inflorescence 
-
Model df Deviance Residual Residual F value P (chi) 
df deviance 
Null 1 1 9 3 88.44 
Species 5 5 1 .48 1 1 4 3 36 . 9546 3 .483525 0.0057 
65 
Together, these differences meant that the number of open flowers per plant also varied 
significantly among the species (Table 4). M monroi and M macrantha had the highest 
average number of flowers open per plant, and M monroi had significantly more than M 
brockiei, M. jorsteri, M laeta and M tenericaulis (Fig. 6) . 
Table 4: Analysis oftotal number of flowers open per plant 
Model 
Null 
Species 
+-' C 
et! 
20 
� 1 5  Q) Q.. 
(j) '-
Q) � 1 0 -
4= 
C 
Q) 
Q.. 
o 5 
o 
df Deviance 
5 105. 1 2  
ab 
Residual Residual 
df deviance 
11 9  
1 1 4 
3 3 4 . 9 9  
229.88 
be 
F value 
1 0 . 0 9  
e 
M. brockiei M. /aeta M. monroi 
P (chi) 
< 0.0000 1 
ab 
M. forsteri M. macrantha M. tenericaulis 
Figure 6: Box plots of the numbers of open flowers per plant. Species that share 
letters above the boxes are not significantly different. 
Finally, the number of flowers in the female phase also varied significantly among the 
species (Table 5) .  M monroi, along with M macrantha, had the highest average 
number of flowers in female phase at any one time, and significantly more than M 
brockiei, M jorsteri, M macrantha and M tenericaulis (Fig. 7) .  
66 
Table 5: Analysis of the number of flowers in the female phase per plant. 
Model 
Null 
Species 
5 
Cf) � 
� 4 0 
4= 
ID Cf) 3 -cu 
.c 0.. I 
ID 2 cu 
E 
ID 
LL 1 
O �  
df Deviance Residual Residual F value 
df deviance 
1 1 9  1 86 . 5 2  
5 64. 66 1 1 4 1 2 1 . 8 6  1 2.02 
b 
ab 
a a a 
I-----! I-----! D 
M. brockiei M. !aeta M. monroi 
a 
P (chi) 
< 0 . 0000 1 
M. forsteri M. macrantha M. tenericaulis 
--� 
Figure 7: Box plots of numbers of flowers in  the female phase per plant. Species that share 
letters above the boxes are not significantly different. 
Dichogamy 
On average, Myosotis monroi flowers spent nearly 25% of the time in the female phase 
before the anthers dehisced (Table 6) .  M. macrantha spends longer in this phase than 
the other species studied, but the variance in the proportions of flowers in each phase 
was high and so these differences among species were not significant (Binomial 
ANOV A, P = 0.225). 
67 
Table 6: Duration of sexual stages (percentage) inferred from the average proportion of flowers in each 
phase (n=20 for each species) 
" '"  
Species Female St dev Male phase St dev Post pollination St dev 
phase phase 
.  -
M. brockiei 10 .8  0 .4  24. 1 0.6 65 . 1 1 . 9 
M laeta 8. 3 0 .4  25.0 0 .7 66.7 LO 
A1. monroi 23 . 5  2 . 1 54.6 3 .7 2 1 . 8  1 .6 
M. macrantha 25.6 0 . 8  47.6 1 . 2  26.8 1 . 1  
M. forsteri 12 .7 0 .4  1 5 .5  0 .5  7 1 .8 0 . 8  
M. tenericaulis 9 .8  0 .4  3 1 .7 0 .7 58.5 6 .0  
There appears to be no relationship between dichogamy and selfing rate (Fig. 8) .  
Although the two species with the shortest dichogamy do have very high selfing rates, 
the pattern does not continue. There are two separate groups of data, with one unusual 
point (M forsteri (Central Otago) - high selfing rate and long time spent in female phase) 
and the intermediate one of M. australis vac lytteitonensis, which has a mixed mating 
system. 
1 .0 ... 
g 0.8  
'-2 o Cl. 
e 0.6 � Cl. 
......., 
Q.l 
"§ OA ... 
Ol 
C 
t;:: 
(ii 0 .2  � Cl) 
0_0 � 
I I 
.min 
• spa 
I I 
o 5 
lae • 
I I 
• • for (N) 
ten 
. Iyt 
bra 
• 
• col 
r r 
1 0  1 5  20 
Dichogamy 
I I 
• 
for (CO) 
man 
• • mac 
I r I 
25 30  35 
"-. 
'. 
". 
" .. 
min: M. 'minutillora' 
spa: M. spathulata 
ten: M. tenericau/is 
for(N): M. forsteri 
(Nelson) 
for (CO): M. forsteri 
(Central Ob go ) 
lyt: M. a.ustrabs 
' Iytteltonensis' 
lae: M. laeta 
bro: M. brockiei 
col: M. colensoi 
mon: M. monroi 
mac: M. macrantha 
Figure 8: Dichogamy (% time spent in female phase) graphed against the se1fing rate 
(seed set/ovule when pollinators are excluded) . Data were extracted from  this chapter, 
chapter two and Robertson and Lloyd, 1 99 1 )  
6 8  
Discussion 
A small amount of pollination does occur during the precocious phase of Myosotis 
monrOl . Although the level of pollination at the precocious phase is low, the small 
additional amount of cross-pollination this mechanism allows may be a sufficient 
selective force to maintain this phase. Hand pollinations of precocious buds indicate that 
the stigma is receptive during this phase although these flowers set significantly less seed 
than that set by hand-pollinated open flowers. The average seed set by hand pollinated 
flowers at the precocious stage of 2 .7  seeds per flower is 77% of the 3 . 5  seeds p er 
flower that is set on average by those pollinated at the open phase. Therefore, stigma 
receptivity at this early stage of the female phase appears to be about three/quarters 
complete. The precocious style does effectively increase the length of the female phase 
in M monroi, thereby increasing chances for cross-pollinations. 
This study is the first to find precocious styles with receptive stigmas. In this case, stylar 
precocity does indicate protogyny, but as shown by Hoc et al. ( 1 994), stigma receptivity 
must be proved. I have shown that the stigmas are receptive during the precocious phase 
and that some pollination is occurring during this phase. 
In terms of their phenology, all species were found to differ significantly in the number of 
inflorescences per plant, the number of open flowers per plant and per inflorescence, and 
in the number of flowers in the female phase. They did not differ significantly in the 
duration of the female phase. 
Myosotis monroi and A1 macrantha have the l ongest relative female phases of the 
species studied. M macrantha, with funnel blossom flowers, also has a relatively large 
floral display and sometimes has a precocious phase, but this is not consistent. The 
prolonged time spent in the female phase by these two species suggests some selective 
advantage occurs for this mechanism, which may promote outcrossing. It seems likely 
that the longer the female phase, the more chance there is of being fertilized with pollen 
from another flower. While M. monroi has a more consistent precocious bud phase than 
M. macrantha, M. macrantha has the longer relative female phase. By contrast, M. 
hrockiei and M. iaeta, b oth brush blossom flowered species, have much smaller floral 
displays and shorter relative female phases. Having a smaller floral display size will 
reduce the number of potential geitonogamous pollinations. The shorter female phase 
69 
period may be a mechanism to allow pollination with one visit, rather than two . It i s  
thought that the advantage o f  herkogamous separation o f  sexual p arts over the 
dichogamous separation is that both pollen receipt and dispatch can be achieved with one 
visit to the flower (Webb and Pearson, 1 993) .  Webb and Pearson ( 1 993) considered this 
system could maintain some degree of outcrossing when the chances for insect 
pollination are poor. Therefore, under these circumstances, selection would favour a 
reduction in dichogamy and this is the case for M. brockiei and M. laeta. This type of 
separation of phases may help these rare species persist and explain, at least in part, how 
they manage to exist in relatively small populations. M brockiei and M. laeta are the 
two that are considered most at risk of those taxa included in this study (de Lange et al. 
1 999) . 
Because of the large floral display of M monroi, there is ample opportunity for b oth self­
and cross-pollination to occur. Incomplete dichogamy and herkogamy are not able to 
prevent self-pollination occurring in self-compatible plants (de Jong et al. 1 993) .  
Particular types of dichogamy and herkogamy influence the levels of autonomous and 
geitonogamous polIinations that may occur. Empirical studies show levels of 
geitonogamy can be substantial and will increase with floral display size (de Jong et al. 
1 993) .  Protogyny and approach herkogamy are considered to be more likely to evolve 
when the avoidance of self-pollination is the selective force (Lloyd and Webb, 1 986 ;  
Webb and Lloyd, 1 986) . In species that require a vector to  achieve pollination, there will 
also be selective pressure to increase the size of the floral display to attract pollinators. 
However, increasing the size of floral display will increase intra- and inter-floral self­
pollinations, when the form of dichogamy is  incomplete. The relative synchrony of the 
phases between plants will offer some protection against such self-pollinations. In 
addition, the ability to increase the relative length of the female phase, will als o  improve 
the chances of receiving cross pollen, p articularly when there is the synchronous 
flowering rather than the sequential type operating as in the other b rush blossom species 
studied. 
All New Zealand Myosotis specIes studied to date that exhibit dichogamy are 
protogynous (Robertson, 1 989; Chapter two). The known exception is M. 'minutiflora' 
which was found to have no female-only phase at all and self-pollination occurs almost 
immediately such that there is very little opportunity for outcrossing to occur (Robertson 
and L1oyd, 1 99 1 ) . There is considerable variation in the length of the female phase 
70 
across the range of species for which this has been measured, and even among 
populations of the same species. The relative time M forsteri spent in the female phase 
contrasts with Robertson' s ( 1 989) findings. He found M. forsteri (Central Otago), an 
initially herkogamous species, spent 3 3 %  of its time in the female phase, while I found 
M. forsteri (Flora Valley) spent just under 1 3%.  M. forsteri is a highly variable specie s  
morphologically. Therefore it i s  not surprising to find such variability in dichogamy. 
Individuals from different populations will be under different selection pressures and this 
is represented by the different times spent in different phases. 
The generally accepted view of the direction of mating system evolution is that it will 
usually proceed from outcrossing to selfing (Raven, 1 973 ;  Lande and Schemske, 1 985 ) .  
However, a s  much of  the extant flora of  New Zealand, including Myosotis, is thought to  
have arrived via recent long distance dispersal (e.g .  Winkworth et al.  1 999), selfing is the 
more likely ancestral state for these taxa. Outcrossing types are thought to have arisen 
secondarily in New Zealand during subsequent speciation that has occurred as new 
environments have emerged (L1oyd, 1 980) .  Within cosexuaI plants the most effective 
means of promoting outcrossing is via dichogamy and less so via herkogamy (Webb and 
Pearson, 1 993) .  Herkogamy, the spatial separation of stigma and anthers, is thought to 
have evolved from dichogamy to maintain outcrossing, but unlike dichogamy, requires 
only one visit for pollination (Webb and L1oyd, 1 986; Webb and Pearson, 1 993) .  All 
species in this study exhibit varying levels of incomplete dichogamy, herkogamy and 
selfing ability. If the ancestral state for the breeding system of New Zealand Myosotis 
was autogamy, then the varying levels of dichogamy and herkogamy found among the 
taxa may assist in testing the above ideas about the evolution of mating systems. 
However, although the groups of species separate out into three distinct groups, there is 
no evidence to suggest a direction for mating system evolution with this data set. These 
aspects of floral evolution are probably under many selection pressures, with reticulate 
evolution possibly occurring within populations of many taxa, p articularly those with 
mixed mating systems, but possibly very little gene flow among populations. Within the 
brush blossom taxa, there are two clearly defined means by which pollination is achieved; 
large floral displays accompanied by synchronous flowering or small flowering displays 
accompanied by sequential flowering. 
7 1  
CHAPTER FIVE 
Rarity in NZ Myosotis L. 
Abstract 
Rarity is generally considered " the precursor to extinction" (Darwin, 1 872). However, 
there are several different forms of rarity and not all rare species are threatened. I 
examined the different rarity patterns observed within New Zealand Myosotis. New 
Zealand Myosotis species are never common, all are rare in different ways and some 
species are threatened. Some species  are known to occur at one locality where they may 
be  locally common, others may occur in two or more widely disj unct geographic areas, 
while others may be widespread but never common where they occur. I compared the 
local abundance, disjunctions and distribution patterns of 3 3  taxa of Myosotis to aspects 
of their morphologies, including traits related to breeding system, dispersal and life­
history. Taxa requiring pollinators to set seed had smaller range sizes and higher local 
population densities than those that were able to self-pollinate. Apparent adaptations for 
dispersal and life-history traits were not correlated with range size .  The disjunct 
distributions exhibited by some taxa within the genus were not associated with any of the 
morphological traits. 
I ntroduction 
The word rare has different meanings and is used to describe many different patterns of 
density and distribution. Gaston ( 1 994) defines rarity 'as the state of having low 
abundance and/or a small range size' .  However, plants can be rare in different ways and 
several authors have defined different types of rarity (e.g. Rabinowitz, 1 98 1 ;  Fiedler and 
Ahouse, 1 992) . Essentially these different forms represent particular range, distribution 
and abundance patterns within different spatial (e. g. Rabinowitz, 1 98 1 ;  Gaston, 1 994) 
and temporal scales (e.g .  Fiedler and Ahouse, 1 992) . There is generally a positive 
correlation between geographic range size and local abundance (Brown, 1 984; Lawton, 
1 993 ; Gaston, 1 996). However there is a lot of variation such that individual taxa can be 
72 
locally abundant but only have a small geographic range and others may be widespread 
but in consistently low population size (Rabinowitz et al. 1 986). Rabinowitz ( 1 98 1 )  
classified seven forms of rarity distinguished by dichotomous differences in local 
population size (everywhere large-everywhere small), habitat specificity (broad­
restricted) and geographic distribution (wide-narrow). However, quite often studies of 
rare plants fail  to address the different types of rarity (but see Kunin and Shmida, 1 997) . 
There i s  little doubt that however rarity i s  defined, perhaps with the exception of 
catastrophic events, it will always precede extinction, and it i s  for this reason that I am 
interested in this aspect of plant conservation ecology. 
Rarity corre lates 
An important aspect of the study of rare plants is in understanding their reproductive 
biology. Rare-common congener difference studies have shown rare plants differ from 
their more common relatives in aspects of their reproductive biology and di spersal traits. 
Rare plants tend to have lower levels of self-incompatibility, a bias toward asexual 
reproductive pathways, lower overall reproductive effort and poorer dispersal ability 
(Kunin and Gaston, 1 993) .  Generally, these studies do not discriminate between 
different types of rarity (Kunin and Shrnida, 1 997) and actual tests of the differences are 
not common (Thompson et al. 1 999). Plants with different breeding systems are likely 
to have different population structures and range sizes. Plants growing at low local 
density are more l ikely to be able to autonomously self-poll inate (Kunin and Shmida, 
1 997). Autonomous selfers can potentially grow, reproduce and colonise a new area by 
the germination of just one seed. They do not require the presence of others to 
successfully reproduce and so can establish as isolated populations. Therefore, we could 
expect that their range size will not be constrained by their breeding system and other 
factors will be important in limiting or improving colonisation successes. Non­
autonomous plants require local population densities at levels that ensure an adequate 
supply of pollen and can attract vectors to achieve pollination. A single seed may 
disperse into a new area and germinate, but if flowers are never pollinated, and 
vegetative reproduction is limited, successful colonisation may not occur. 
The dispersal abilities of species are expected to have an effect on their distributions. 
Several researchers have found correlations between dispersal ability, local abundance 
and range size (e.g. Rabinowitz, 1 978; Rabinowitz and Rapp, 1 98 1 ;  Oakwood et al. 
73 
1 993 ; Quinn et al. 1 994) . However, a reanalysis of the Quinn et al. ( 1 994) study by 
Thompson and Hodgson ( 1 996) using the same taxa, a d ifferent classification of 
dispersal in space (i . e. dispersal distance), and new data on dispersal in time (i .e .  seed 
persistence) showed no relationship b etween distribution patterns and dispersal. 
Thompson et al. ( 1 999) in a study of the flora of central England, found dispersal ability 
explained very little of the variation in local range and none of the variation in national 
range for these species. Further investigation is required as there are other factors 
involved in determining distributions. There may be different regimes operating on the 
floras of different countries .  Thompson and Hodgson ( 1 996) believe habitat loss is the 
maj or determining factor in the distributions of plants in Britain. 
Life-history traits of plants may also influence their distributions. Perennial plants and 
those capable of vegetative reproduction may be able to offset a lack of recruitment 
during years of poor pollination (Quinn et al. 1 994) and may be  able to spread more 
effectively than those species that are annual and have no ability to vegetatively 
reproduce. 
New Zealand Myosofis L. (Boraginaceae) 
A range of rarity types (sensu Rabinowitz, 1 98 1 ) has been observed within the N ew 
Zealand taxa in the genus and 3 3  % are considered threatened in some way (de Lange et 
al. 1 999) .  Some species are point endemics, known to occur at only one locality, while 
others are found sporadically throughout most of New Zealand. For example, the point 
Figure 1: Examples of rarity patterns seen in  the genus Myosotis. A1. albo-sericea (left), A1. 
arnoldii (center) and M forsteri (right). 
74 
endemic Myosotis alho-sericea i s  known from one locality where it is abundant (Fig. 1 ) . 
Myosotis arnoldii is also abundant where it occurs, but has a disjunct distribution, with 
one maj or locality in northwest Nelson and the other in Marlborough. Myosotis fbrsteri 
occurs sporadically throughout New Zealand and although it is the most often recorded 
species of the New Zealand Myosotis group, it is never abundant where it occurs. 
All New Zealand Myosotis species studied so far have been found to be self-compatible 
(Chapter two). There is a range of pollinating mechanisms from autogamous selfers 
through to those that require pollinators to achieve fertilisation (Robertson and Lloyd 
1 99 1 ;  Chapter two).  Species that require pollinators, have been found to be pollen­
limited in low density patches (Chapter three) . 
The aim of this study is to test whether morphological traits, particularly those related to 
reproductive biology, have any association with the range of distributions, population 
disjunctions and local densities that are seen in New Zealand Myosotis. 
Methodolog ical d ifficult ies 
This type of study, in which comparisons are made between rare and common congeners 
in an effort to understand more about rare species, has been criticised by various authors 
for several reasons (e.g .  Kunin and Shmida, 1 997). A problem cited by Kunin and 
S hmida ( 1 997) is that only a single measure of rarity has typically been used in each 
study. Plants can be rare in different ways and at different spatial scales. S ome studies 
are of point endemics with dense local populations, while others are of sparse taxa with 
low densities but wide geographic ranges. Kunin and Shmida ( 1 997) recommend 
measuring rarity at different spatial scales in an effort to allow for the different types of 
rarity observed. 
The non-independence of the traits of related species is a further problem that has been 
identified with these types of studies i . e. that suites of traits shared by species may not be 
independently acquired but inherited from a common ancestor (Brown, 1 984; Harvey, 
1 996; Kunin and Shmida, 1 997). It is therefore important to take phylogeny into 
account when making interspecific comparisons (Harvey, 1 996). Unfortunately a 
resolved phylogeny does not exist for New Zealand Myosotis. Molecular work in the 
genus has so far found little difference among the New Zealand taxa and this is attributed 
to very recent speciation events within New Zealand (Winkworth et al. 1 999). In the 
75 
absence of a resolved phylogeny, it would be tempting to use the taxonomic structure of 
the genus, as described by Moore in Allan ( 1 96 1 ), as a surrogate for phylogeny. 
However, Moore admitted, "though the position of the anthers in relation to corolla 
scales is used in the first division of the key below, there is no firm conviction that this 
leads to the most nearly natural arrangement" (p 807). For this reason (see Chapter 6 
for a full discussion of this treatment) I d o  not consider Moore' s classification system 
appropriate for this type of phylogenetic correction. 
Methods 
Measurements were made of rarity patterns and various reproductive, life history and 
dispersal parameters in 3 3  NZ Myosotis taxa (Table 1 ). Herbarium material (CHR -
Landcare Research, Lincoln - see appendix 5 for details of the specimens examined), 
personal observations, and reports (published and unpublished) provided the data. The 
results presented are averages from 1 -5 separate plants. 
Floral Characters: Herkogamy is the spatial separation of anthers and stigma. Species 
that are always herkogamous require a vector to achieve pollination, while those that are 
never herkogamous are able to self-pollinate autonomously and do not require a vector 
to mediate this process (Chapter 3) .  An intermediate category is required for those taxa 
that have been found to be initially herkogamous or contain both morphologies within 
populations. 
Growth forms: A woody root system is indicative of a longer-lived species compared 
to those with a fibrous system. Individuals of some species typically consist of a single 
rosette (indicative of shorter-lived species), whereas other species form large clumps of 
several rosettes (indicative of longer lived species) . 
Seed/calyx characters: Myosotis species have dry, shiny nutlets that vary in size from 
0 .9  mm to  3 . 5  mm and may have winged edges (Webb and Simpson, 200 1 ) . Further, the 
calyces may split open fully, allowing seed to drop out at maturity, or have short splits, 
which retain the seeds. In addition, the hairs on the calyces can be strongly, weakly or 
not hooked. 
76 
Table 1: Morphological characters 
Character Units 
Herkogamy mm 
Style length mm 
Filament length mm 
Anther length mm 
Corolla length mm 
Corolla width mm 
Hooked hairs 0, 0 . 5 , 1 
Root system 0, 1 
Rosette number 0, 1 
Calyx split mm 
Calyx length mm 
Calyx ratio proportion 
Seed length mm 
Winged seeds 0, 0 . 5, 1 
_.��Iative seed len�h __ �tio _ 
P = 1 098 
Explanation 
Spatial separation of anthers and 
stigma 
Length from top of ovary to base 
of stigma 
Length from corolla attachment to 
anther attachment 
Anther length 
Length from base of corolla tube to 
top of corolla lobe 
Width of flower 
0 :  none 
0 . 5 : weakly hooked 
I :  strongly hooked 
0: fibrous 
1 :  woody 
0 :  single 
1 :  multiple 
Length of split 
Calyx length 
Calyx split/calyx length; the 
proportion of the calyx that is split 
Seed length 
0: none 
0. 5 :  slightly winged 
1 :  distinctly winged 
Seed length/flower size 
A =  5 1 397 
W =  7664 
No pops 1 4  
Source 
personal observations, 
herbarium material 
Herbarium material 
Herbarium material 
Herbarinm material 
Herbarium material 
Herbarium material 
Herbarium material 
Herbarium material 
Herbarium material 
Herbarium material 
Herbarium material 
Derived character 
Webb and Simpson, 200 1 
Webb and Simpson, 200 l 
Derived character 
Figure 2: Example of how the geographic traits were quantified for Myosotis venosa. P perimeter, A 
area, N number of discrete collection records, W = the length of the minimum spanning tree, No 
pops number of groups of collection records more than a specified distance apart (see Table 2 for more 
detailed explanations) 
77 
Distribution measurements: (Table 2) 
Data for the geographic measurements were taken primarily from the Landcare 
herbarium database (CHIRP). Records were accepted if grid references were supplied 
by the collector or able to be inferred from the locality description. A mapping program 
(Amnesia) was developed by Ian Henderson to plot species distributions and calculate 
the following distribution parameters (see Fig. 2 and table 2). 
Table 2 :  Distribution characters 
� -
... ��.��.����.� .............................. !1��.!.� ............................................. ��P.!�����.�� .............................. ���.��� ...................................... . 
Perimeter kilometres (log Perimeter of the CHIRP 
transformed) minimal convex database/Amnesia 
polygon (= perimeter 
around distribution) 
Area km2 (log transformed) Area of minimal CHIRP 
N 
MST 
Number of 
populations 
Local density 
Occupancy 
Average disJunction 
DisJunction 
Relative disjunction 
Geological 
specificity 
Statist ics 
Number (log 
transformed) 
Kilometres (log 
transformed) 
Number 
(log transformed) 
1 -4 
Number of 
populations/ Area (log 
transformed) 
MSTIN (log 
transformed) 
Kilometres (log 
transformed) 
Longest MST 
lengthIMST (log 
transformed) 
1 -4 
convex polygon area 
of distribution) 
Number of discrete 
collection records 
Length of minimum 
spanning tree 
Number of groups of 
collection records more 
than 10  kilometres 
apart 
Subjective assessment 
of typical population 
density, I being sparse 
and 4 being locally 
dense 
How completely a 
species fills its range 
Average MST branch 
length 
Longest MST branch 
Measure of relative 
disjunction 
Number of different 
geological substrates 
known to occur on 
database! Amnesia 
CHIRP 
database/Amnesia 
CHIRP 
database/Amnesia 
CHIRP 
database/Amnesia 
Andrea Brandon, 
Alastair Robertson, Bec 
Stanley, GeoffWaIls, 
Kath Dickinson, Alan 
Mark 
Derived 
Amnesia 
Derived 
Amnesia 
Geological map of New 
Zealand series 
( 1 :250000) 
S ome problems have been identified with the methods  used in some rare-common 
congener studies, such as the intercorrelation of traits (Kunin and Gaston, 1 993) .  In an 
effort to overcome this problem I have chosen to perform separate Principal Components 
Analyses of morphology and distribution using PC-ORD rather than multiple regressions 
78 
for the data analysis .  In addition, a Canonical Correlation Analysis was performed to 
relate the two datasets using SYS7A T version 8 .0 (SPSS Inc, 1 998) on a subset of the 
characters. Derived characters (calyx split, seed length, W, No pops) were excluded 
from the Canonical Correspondence Analysis to avoid the problem of multicolinearity. 
Results 
peA of morphology 
In the Principal Components Analysis of morphology, 55% of the variance was explained 
by axis one (table 3 lists the traits and scores from the analysis for the first five axes) . 
N early 1 1  % of the variation is explained by axis two. 
Table 3: Pearson correlations between each character and the ordination axes (n == 3 3).  (Correlations 
greater than 0 .400 are shown in bold.) 
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
2 3 4 5 
Herkogamy -0.609 -0.008 0.600 0.246 0.230 
style length -0.925 -0.097 0. 1 80 0.047 0.055 
filament length -0.901 -0.075 0.20 1 0. 1 04 0.049 
anther length -0.836 -0. 1 3 1  0.270 0 .273 0.0 1 1 
corolla width -0.844 0.390 0 . 1 75 0. 1 1 0 0.064 
corolla length -0.940 -OJJ09 0.058 0.208 0.0 5 l  
hooked hairs -0. 0 1 2  0.272 -0.355 0.803 0.336 
Root system -0.643 -0 . 1 56 -0.387 0. 1 93 0.532 
Rosette number -0.694 -0.492 -0. 1 1 5 0.233 0. 1 98  
Calyx split -0.796 0.366 -0.333 0.066 0.250 
Calyx length -0.791 -0. 1 95 -0.235 0.244 0.370 
Calyx ratio -0.227 0.843 -0.236 0 .377 0.048 
Seed length -0.902 -0.059 -0. 1 9 1  0.039 0.00 1 
Winged seeds -0.620 -0.276 -0.531 0. 3 1 6  0.089 
. . .  R.:�.la�iv.e .. ���.d .. lel1.� . . . . . . . . . . . . �:7.4.5 . . . . . . . . .  �O':3.s.� . . . . . . . .  :(J:.2.6.5 . . . . . . ... 0:.0.8.4. .. . . . . . .  0:.I.S.S. . . . . .  
% variance 55  1 0.9 9 .6 8 .4 
All the floral size measurements have high negative correlation scores on axis one. A 
number of other characters correlate negatively with the first axis as well : herkogamy, 
woody root system, multiple rosettes, length of calyx split, calyx length and winged 
seeds. Relative seed length, which was calculated to take flower size into account, was 
positively correlated with axis one indicating that taxa with smaller sized flowers tend to 
have relatively large seeds for their size. Axis two has just two characters with 
correlation scores greater than 0 .400, the calyx ratio with a high positive score and 
multiple rosettes with a high negative correlation. The calyx ratio is independent of 
flower size and negatively correlates with multiple rosettes. Axis three, which explains 
9 . 6% of the variance, has herkogamy as well as the winged seeds loading strongly. 
Herkogamy is correlated with flower size and so also loads on axis one. Axis four, 
which explains 8 .4% of the variance, has the presence of hooked hairs on the calyx 
79 
loading strongly. Axis five, which explains just 4. 9% of the variance, has a positive 
correlation with woody root system. The woody root system loaded strongly on axis 
one as well but exhibited a negative correlation. 
Essentially, axis one is a measure of flower size (Table 3) .  The calyx properties, the 
degree of the split and the presence of hooked hairs, two measures of apparent dispersal 
ability, are not correlated with each other, and they are not correlated with flower size. 
When the geographic measures are overlaid on the ordination of morphology, local 
density is negatively correlated with flower size (axis 1 )  and geological specificity i s  
positively correlated with flower size (Fig. 3) .  Species with smaller flowers have the 
least dense populations and broadest geological tolerance while large flowered species 
are locally dense with more specific geological requirements .  
Local density 
concmna 
• 
amo!dii 
• eximia 
m3crantha 
• 
• 
explanata 
• 
saxosa 
• 
monroi 
• 
goyenll 
• 
colensoi 
• Herkogamy • 1 
. .,::::, 0 .5 
0 0 
Relative disjunction 
suavis 
petiolata 
• 
brockiei venosa 
• 
uniflora 
• 
forsten 
'-----:{-:-:::Iytt-el-:-ton-""...,�-S ---Geological specificity 
':';', traversii v Jraversii 
:::;::: angustata 
rakiura o 
Axis 1 
sp ath ualata/tenen eau;!i s 
'::""�. traversl v :::�::; cantabrica 
0 small white pansa ;::�:�:: 
yellow o 
Area Number of populations 
o 
o pygmaea 
Figure 3: peA of morphological traits with correlation coefficients of distribution traits overlaid 
(graphed if greater than 0.45). Species symbols represent herkogamy class. 
80  
There are no large distributional correlates with axis 2. However axis 3 has several of 
the distribution measures loading strongly (Fig. 3) .  Herkogamy for each species is 
shown overlaid on the ordination diagram of axis one and three. Herkogamy correlates 
positively with local density and negatively with the number of populations and the area 
of distributio n  (Fig 3 ) .  
PGA of  d istribut ion 
Principal C omponents analysis of the distribution data shows that 72 % of the variation 
was explained by axis one, with axis two explaining a further 1 5  %. Table 4 lists the 
distribution measures along with their scores in the analysis. 
Table 4:  Pearson correlations with ordination axes 33 ) .  Correlations greater than 0 . 400 are shown 
in bold. • ...
.
.
............
.
.......... .....
.
..........
.
.........•••••
•
••••
•
•
•• .t'  ••  .,..
-
... .................. r  .......... ......................................................... ....................................................... .................. -••• -•••••••• ..., 
1 
.. . . . . .. . . . . . . . . . 3" . . . . . . • . • . . . . . . . .  : . . . . . . .. .. . . . 
Perimeter 0.967 
Area O.97S 
N 0.869 
MST O.9S5 
Number of populations 0.939 
Local density -0.667 
Occupancy -0.926 
Average disjunciion 1l.663 
0.242 
-0.0 1 5  
-O.41S 
0. 1 36 
-O.22S 
0.286 
-O'(J97 
0.707 
0.030 0.006 
0. 1 63 0.09 1 
0. 175  0.052 
0.020 0.007 
-0.0 5 1  0.000 
0.627 0.259 
-0.262 0. 1 32 
-0. 1 67 0.048 
Disjunction 0.795 0.591 0.030 0.032 
Relative disjunction -0.709 0.641l -0. 1 42 0. 1 42 
'".g�?!?�i��I .�J.l.�S�!}.sj!x. .w . .. . . . c.cccc.c.w •••  !!;l.�.�." . . . . . . :!!392.w . . . . . . :Q.:.!.2.Q"wNc.2.:§1.g .. c 
1 5 .4 
Essentially axis one is a measure of range size (Table 4) . The perimeter, area, minimum 
spanning tree lenf,>th, number of discrete collection records and number of populations 
are all measures of range size and are highly correlated with each other. Geological 
specificity is also highly correlated with range size - the wider range of geological 
substrates a species is found on, the larger the range size. Geological specificity is also 
p artly independent of range as it also loads highly on axis four. Two measures of 
disjunction, the average minimum spanning tree (MST) branch length and the longest 
MST branch are correlated with range size. However, relative disjunction is negatively 
correlated with range size. Species with high scores for relative disjunction have small 
range sizes while those with high scores for longest branch length and average branch 
length have large ranges. Occupancy, a measure of how well a species fills its range, is 
negatively correlated with range size. Species with smaller range sizes fill their ranges 
well while those with large ranges do not . Local density also has a negative relationship 
with range size. Species with small range sizes have high local densitie s  while those with 
large range sizes have low local densities .  The measures of disjunction, while loading 
8 1  
quite strongly on axis one are also loading on axis two. Axis two is  the best measure of 
disjunction since the traits that score highly on this axis are those that describe large gaps 
in the distribution. Axis three has local density loading quite strongly, but it explains less 
than 6 % of the variance. Geological specificity loads on axis four as well as axis  one, so 
while it i s  correlated with range size there are unrelated influences, but axis four explains 
just 4 % of the variation. 
The morphological traits were then overlaid on the ordination of distribution characters 
(Fig. 4) .  
oreophifa 
• 
a!boseri M • 
tJ) 
·x « 
laeta 
cheesemanij 
matthe'Wsii 
o 
traY_can 
::��:?, 
0'" white 
osuavrs 
angustata 
o 
explanata 
o lytteltonensis o 
Axis 1 
o 
macrantha 
;:�*? 
eicil:rall 
o 
yellow 
o 
+pygmae 
+ forstert 
+ spathten 
Local density 
+ 
0 2 
2.5 
:��;�:: 3 
• 4 
Figure 4: peA of D istribution with morphology overlaid (graphed if greater than 0 .45), species symbols 
represent local density class. 
Small herkogamy is the best predictor of range size (Axis 1 ), with filament length also 
showing a strong correlation on the first axis .  Species that are always herkogamous have 
smaller range sizes. Filament length, which i s  associated with herkogamy, i s  also a good 
8 2  
predictor of range size. Seed length relative to flower size negatively correlates with 
range size. Plants with wider distributions have longer seeds in relation to their flower 
size. None of the apparent dispersal attributes correlated with range size. The presence 
or absence of hooked hairs, the degree that the calyx is split and the winged seed 
morphology had no relationship to range size. Seed size might also be expected to have 
some correlation with range size, as small seeds are easier to disperse by wind, but it 
does not . It correlates with flower size. The life history traits were not correlated with 
range size. The disjunction measures, which have loaded o n  axis two in the first PCA, 
are not correlated with any of the morphological traits included in this study. 
CCA of combined data 
The canonical correlation analysis for the combined set of traits was significant (p 
0 . 045)  and the Bartlett test of residual correlations found just the first axis  was 
significant (p = 0 .0 1 5). In the analysis, all floral size characters, herkogamy, life history 
and relative seed length have high canonical loadings on Axis 1 (Table 5) .  Only the 
apparent dispersal traits have low loadings. All distribution measures used in the analysis 
have high canonical loadings. 
This single, significant axis in the CCA closely parallels a combination of the two Axis 
one' s from the separate PCA' s .  
Table 5 :  Canonical correlations for the combined dataset (correlations greater than 0 .400 are shown in 
bold). 
Morphological Characters 
Distribution Olaracters 
Herkogamy 
Style length 
Filament length 
Anther length 
Corolla width 
Corolla length 
. . . . . . . . . .  C:;:llloIliclll.l()lldiI1gs . .  -0.641 
-0.662 
-0.683 
-0.582 
-0.577 
-0.424 
Hooked hairs on calyx 0. 1 43 
-0.486 Root system 
Rosette number 
Calyx length 
Calyx ratio 
Winged seeds 
Relative seed length 
Perimeter 
Area 
N 
Local density 
Occupancy 
Average disjunciion 
-0.402 
-0. 1 1 0 
-0 .040 
-0. /98  
0.538 
0.607 
0.591 
0.538 
-0.852 
-0.456 
0.482 
Disjunction 0.471 
Relative disjunction -0.457 
• • . • • • • . • • •.•.•••• •...•••••••• · • • • • • • • •  ·•· ••••• w • • • . • • • • • •  g.�2!2.1;l!.��!.�p.�.�i!!.�.i.!X .... m • • • . • . • •  w • • • • • . • • • • • • • . . •  �57.2 ... 
83 
2 
1 -
0 -(J) .-
°ffi ..... .-
() - 1 I-
..c 
Q.. 
� - 2 I-0> 
0 
Q) 22 
(9 - 3 I- -
-4 
-4 
I 
1 1  _ 
I 
-3 
I I I 
1 7_ - 7  -3 -
-1 8  6_ _ -4 25 20 29 1 - -39 -- • 1 2l -1 3 1 9  12 - 1 5_ 5 16- 2e- 8 2 1 - � - 1 4 �6-2 � 10  
27 .. 33  -30 
I I 
-2 - 1  
-
-
-
I 
0 1 
M o rp h o l o g i cal traits 
1 M. albo-sericea 
2 M. angusrala 
3 M. arnoldii 
4 M brockiei 
5 M. cheesemami 
6 M. colensoi 
7 M. concinna 
8 M elderillyallii 
9 M eximia 
1 0  M explanata 
1 1  M forsteri 
12 M goyenii 
1 3  M laeta 
1 4  M. australis var. 
lytte/(onensis 
1 5  M. macranrha 
16 M. mal/hewsii 
17 M. monroi 
1 8  M oreophila 
19 M. petialata vaT. pansa 
20 M petialara var. 
petialata 
2 1  M. petialata var. 
pottsiana 
22 Ai. pygmaea sI 
23 M rakiura 
24 M "saxati lis" 
25 M. saxosa 
26 M "small white" 
27 M sparhulara/ 
tenericalllis 
28 M. SlIavis 
29 M. (raversii var. 
cantabrica 
30 M. traversii vaT. 
rraversii 
3 1  M uniflara 
32 M. venasa 
33 M. "yellow" 
Figure 5: Graph of the fi rst canonical axis of the canonical correlation analysis. I t  presents the 
relationship between tJle scores for the morphological variables with the scores for the geographic data 
for each species. 
Fig. 5 shows the single significant canonical correlation aXIS separated into 
morphological and distributional components. Each species position is calculated by the 
fraction of its total score attributable to morphological traits plotted against the fraction 
attributed to distributional traits. The species comprise a gradient from selfing, small 
flowered, locally sparse and widespread taxa at the bottom left to pollinator-requiring, 
large flowered, locally dense and geographically restricted taxa at the top right. The lack 
of outliers indicates the predictability of distribution by floral morphology in this 
combined axis. 
84 
Discussi on 
These results show that breeding system and floral structure together predict accurately 
the range size of New Zealand Myosotis taxa A key aspect of floral morphology that 
separates species is herkogamy (spatial separation of anthers and stigmas) and the 
associated range of flower size. Species with relatively wide distributions have little 
herkogamy, small flowers and are able to self-pollinate while those with small range sizes 
have significant herkogamy, larger flowers and are dependent on pollinators for seed set 
(see Chapter two) .  The pollination system thus appears to affect range size in New 
Zealand Myosotis. Local density, which is negatively correlated with range size, is also 
highly correlated with pollination system. As expected, pollinator-requiring taxa tend to 
occur in locally dense populations while self-pollinating taxa are generally found in low­
density populations (as shown in Chapter three). It is not surprising that pollinator­
requiring taxa are range-restricted although the link between pollination ecology and 
range size is not universal (Karron, 1 987 cif Kunin and Shrnida, 1 997) . In fact, range 
size and abundance are positively correlated in several taxonomic groups (e .g. birds -
Gaston, 1 999) .  In New Zealand Myosotis, however, range size and local density or 
abundance are negatively correlated . The pollination system provides a mechanism by 
which this pattern can be maintained. Individuals of poll inator-requiring taxa that have 
dispersed too far from the parent population could  be selected against as a result of 
density dependence for pollination. 
Geological specificity is also correlated with breeding system. Pollinator-requiring taxa 
are found on fewer different geological substrates than those that self-pollinate. This 
may indicate that these taxa are habitat specialists, and that this requirement also restricts 
their range size. Ecological factors such as soil conditions may play a role in l imiting 
species distributions. Alternatively, this may be an incidental consequence of a restricted 
distribution. 
Occupancy, or the measure of how well a species fills its range, is negatively correlated 
with all the geographic measures of range size. Species with large range sizes do not fill 
their ranges as completely as species with small ranges. Occupancy is also correlated 
with local density, as species that are locally dense fill their ranges more completely that 
those that are locally sparse. However, occupancy, as I have defined it, may simply be 
8 5  
related to range size i .e .  point endemics will have an occupancy score of 1 00%. 
A surprising result is  that the apparent seed dispersal aids (calyx properties, seed size and 
winged seed morphology) are umelated to the distribution patterns of New Zealand 
Myosotis. It may be difficult to test for any relationship between present-day dispersal 
aids and range size, since dispersal ability has been found to respond rapidly to changes 
in selection pressure (Cody and Overton, 1 996). McGlone et al. (200 1 )  conclude that 
current range patterns for plants found in New Zealand have arisen through Pleistocene 
extinctions, speciation and dispersal. It is possible that the dispersal aids that influenced 
range sizes are no longer present within this group, or perhaps they no longer function 
because of changes in climate or the loss or gain of animal vectors, but I found no 
evidence to support the concept that dispersal ability explains present day distributions. 
During the last 1 0  000 years (since the last glacial), all available habitats may have been 
filled. Therefore it could be that the most influential aid to dispersal during much of that 
time has since been eliminated through selection. Range size was negatively correlated 
with seed size, but positively correlated with relative seed size (adjusted for flower size) 
(Fig. 4). Small seeds can be expected to be more easily dispersed (Eriksson and 
lakobsson, 1 999) but having a larger nutritional store gives seeds a competitive 
advantage over those with smaller reserves in seedling establishment (Gross, 1 984). It 
appears that while  selfers do have smaller seeds, they maintain a relatively larger 
investment in each, possibly reflecting a trade-off between dispersal rate and 
establishment success. The selfers also produce constantly high proportions of seed per 
flower (Chapter 3 ), so in addition to making a relatively large investment per seed, they 
are also producing more seed per flower than vector-requiring taxa. 
There are two processes that can give rise  to population disjunctions. Local extinctions 
of populations that previously connected the now disjunct populations could result in 
present day distribution disjunctions. Alternatively, long distance dispersal and 
subsequent successful colonisations could also result in such population disjunctions. 
These two processes might be expected to relate to different aspects of morphology; 
long distance dispersal with dispersal aids  and local extinctions with breeding system. 
Neither pattern is supported here. Population disjunctions (axis two of the distribution 
PCA) were not correlated with any of the morphological traits .  
Distribution patterns were independent of the life history traits (rosettes usually single or 
86 
multiple - used as a measure of vegetative reproduction, and root system woody or 
fibrous - used as a measure of plant longevity). These traits do not appear to be 
important determinants of distribution in this genus. 
Stanley et al. ( 1 998) have argued that environmental factors, such as wind exposure and 
snow melt, play an important role in governing the demography of Myosotis oreophila, 
an alpine, point endemic. It may be that ecological factors play a greater role in 
determining Myosotis species distributions than my results have indicated . The 
putatively outcrossing taxa were generally restricted to specialised substrates, which 
suggests that specific soil conditions may play an equally important role in controlling 
distributions. 
Conservat ion 
Distinguishing between rare species that are threatened from those that are not, IS an 
important goal of conservation prioritisation and the sensible allocation of limited 
resources. My results can assist threat a ssessment and conservation ma..'1agement for 
New Zealand Myosotis. Locally dense, geographically restricted taxa are pollinator 
requiring while sparse, widespread taxa are selfing. Cases that break this general rule 
may be used to identify taxa at risk. For example Myosotis australis var. lytteltonensis i s  
now known from just one location where i t  is not locally abundant . It has declined 
seriously in recent times (Pender, 1 999). This species is at greater risk of extinction than 
one that is known from just one locality but is locally abundant, such as M albo-sericea. 
Similarly, M. petiolata var. petiolata is known to survive certainly from only one oftwo 
recorded disjunct localities. This population of around 200 individuals occurs within a 
very small area and requires pollinators to set seed. This species is therefore more 
threatened than M arnoldii, a species with a similarly disjunct distribution, but which i s  
abundant at both localities. 
This knowledge can also be applied to managing populations both in situ and ex situ. 
Hand pollinations may be required to assist seed production for species that have 
dropped to low numbers, or are being grown in unnatural conditions, such as a 
glasshouse. When designing translocations, those species that require pollinators should 
be established at population densities that ensure adequate pollination. 
87 
CHAPTER SIX 
Species l i mits in the Myosotis forsteri Lehm.lvenosa Col. complex 
Abstract 
"Though the position of the anthers in relation to corolla scales is used in the first 
division of the key below, there is no firm conviction that this leads to the most nearly 
natural arrangement" 
Moore (in Allan, 1 96 1 )  
In the most recent taxonomic treatment, New Zealand Myosotis is initially split into two 
major clades depending the degree of anther exertion exhibited by the flowers. Anther 
exertion depends largely on the length of the filament. Trjs has led to the recognition of 
species that cannot be distinguished in any other way and often results III 
morphologically similar taxa being grouped with morphologically less similar taxa. I 
examined species limits in Myosotis forsteri and M. venosa, a pair of vegetatively similar 
speCIes. Fil ament length determines the degree of self-pollination that can occur and 
whether or not reproduction is assured. The use of filament length as a taxonomic 
character is not considered appropriate to make the initial division in this group of plants .  
Introducti on 
New Zealand is the southern hemisphere centre of diversity for the genus Myosotis L. 
(Boraginaceae). Traditionally, the genus has been divided into sections based on corolla 
scale morphology and anther position in relation to corolla scales (Robertson, 1 989). 
Lucy Moore carried out the last treatment of New Zealand Myosotis (in Allan, 1 96 1 ). In 
this treatment, Moore accepted two sections, Myosotis and Exharrhena, for the New 
Zealand taxa. Moore admitted, "though the position of the anthers in relation to corolla 
scales is used in the first division of the key below, there is no firm conviction that this 
leads to the most nearly natural arrangement" (Allan, 1 96 1 ;  p 807) . It is thought that 
this method of classification has led to the recognition of species on the basis of relative 
88 
anther exertions that could not be differentiated any other way (Robertson, 1 989). 
The major influence anther exertion has in Myosotis is whether or not autonomous self­
pollination can occur. Studies have been conducted on the breeding systems of several 
species of New Zealand Myosotis with a range of anther exertions (Chapter two, 
Robertson, 1 989). All species studied to date are fully self-compatible. However, some 
species are able to self autonomously while others require a vector to achieve poll ination 
depending on the degree of herkogamy and dichogamy exhibited by the flowers (Box 1 ) . 
Some species have mating types that comprise a mixture of the two, and these species 
are considered intermediates along an out-crossing-selfing continuum (Robertson and 
Lloyd, 1 99 1 ) . Robertson and Lloyd ( 1 99 1 )  found selfing ability was accompanied by a 
reduction in style length, pollen allocation and corolla size. 
Box 1 
Always herkogamous: where the stigma is 
initially exserted beyond the anthers and 
remams so.  
Initially herkogamous: where the stigma 
initially protrudes but corolia extension hfts the 
anthers above the stigma during anthesis.  
Never herkogamous : where the anthers and 
stigma are in close contact throughout. 
Robertson and Lloyd ( 1 99 1 )  
Cheeseman ( 1 925) made the comment that several species of  Myosotis "greatly resemble 
one another in habit and foliage, although widely different in the flowers" .  Two species 
that are very difficult to distinguish in the absence of flowering material are Myosotis 
forsteri and Myosotis venosa. In the case of M forsteri Moore notes of "plants . . .  
collected . . .  on many North Id .  mountains, (the) relative lengths of filaments, of anthers 
and of styles vary . . .  tending to bridge the gap between this species and M venosa" 
(Allan, 1 96 1 ;  P 822). Of M. venosa Moore notes, "this species . . .  more closely 
resembles M. forsteri. Without the corolla and stamens specimens can be determined 
only tentatively by the slightly finer and more spreading hairs and the long style with 
clavate stigma" (Allan, 1 96 1 ;  P 823) .  
One of the study taxa used in the Robertson and Lloyd ( 1 99 1 )  paper was M. forsteri. 
They showed this species is initially herkogamous (see Box 1 ), protogynous and has a 
89 
"delayed" selfing mode of fertilisation (sensu L1oyd, 1 979). In this species there i s  a 
chance for cross-pollination to occur during an initial female-only phase when the stigma 
is receptive prior to anthesis. By the end of this initial female only phase, due mainly to 
continued growth of the corol la, the anthers contact the stigma at anthesis, and any 
unfertilised ovules are spontaneously fertilized (Robertson and L1oyd, 1 99 1 ) . Seed 
production in this species i s  never pollen limited (Chapter two, Robertson and L1oyd, 
1 99 1 ) . 
The aim of this study is to determine whether relative anther exertion i s  an appropriate 
taxonomic character on which to initially segregate New Zealand Myosotis taxa, using 
two species that are very similar vegetatively: M. jorsteri and M venosa. Taxonomic 
characters such as floral and vegetative traits that are used to distinguish the two taxa are 
compared. The pollination requirements of the two species are compared and discussed 
in relation to mating system evolution and speciation. 
Materi als and methods 
Study taxa 
M. jorsteri and M venosa are short lived, forest herbs. Details of the floral differences 
can be seen in the photos of their flowers (Fig. 1 ) . M. jorsteri, on the left, has anthers 
borne on short filaments that are positioned within the corolla tube with their tips at the 
level of the corolla scales. The stigma is in contact with the anthers . In contrast, the 
anthers of M. venosa are borne on filaments such that they are held well above the 
corolla scales and are spatially separated from the stigma. 
M. venosa occurs within the range of M jorsteri (Fig. 2). M jorsteri, has a much wider 
geographic distribution than M venosa. Chapter five shows that pollination 
requirements are the best predictor of range size in New Zealand Myosotis. 
90 
Figure 1: Details of the floral differences can be seen in these photos. The anthers of M. jorsteri, 
on the left, sit within the corolla tube and are in contact with the stigma. The anthers of M. venosa 
are exserted beyond the corolla tube and are not in contact with the stigma, which is held well 
above the level of the s cales 0 n a l ong s tyle. P hotos, A lastair R obertson ( left); B ruce S unnex 
(right). 
M.jorsleri M. venosn 
100 km '00 km 
Figure 2: Distributions of Myosotis jorsteri (left) and M. venosa (right) based on collection 
records held at Landcare herbarium at Lincoln. 
9 1  
Morpholog i ca l  measurements 
Herbarium material was used for this study. Specimens were chosen to ensure that the 
full geographic range of the collections was sampled. Flowers were soaked in glycerine 
to re-hydrate them. Measurements were taken, under a dissecting microscope, of the 
following quantitative traits :  
Leaf lamina length and width, petiole length, degree the calyx is split, peduncle length, 
style length, filament length, anther length, and corolla  length and width. 
Additional observations were made on two qualitative traits; stigma shape and filament 
attachment position. For each of the above specimens, whether stigmas were clavate or 
capitate and where the filament was attached in relation to the corolla scales were 
recorded. 
The specimens examined and the raw scores for all traits are listed in appendix 6 .  
Data analysis 
F or the multivariate statistical analysis I used SYST A T version 8 . 0 .  A step-wise linear 
discriminant analysis was performed on the quantitative morphological variables, in order 
to determine which variables are most useful for discriminating between the two species .  
Autofert i l ity experiments 
P lants were caged to exclude  pollinators to determine the pollination requirements at one 
p opulation of each species in the Cobb Valley, Nelson, New Zealand. Seed set by plants 
in pollinator-excluded conditions were compared to that set by plants in unmanipulated 
conditions. Herkogamy was measured for several plants in each of these populations. 
Geographic variation 
Measurements of corolla length and width and lamina length and width were mapped 
against geographical position to determine whether clinal variation exists in  vegetative 
traits and whether it is shared between the two species. 
92 
Results 
Morpho logy 
Stepwise discriminant analysis ofthe morphological variables stopped at the last variable. 
The final model found by backward stepping contains just one variable: filament length 
(Table 1 )  with an F-to-remove value of 249. 04 (i .e .  greater than 3 . 9, the critical F value) . 
This data set provided just one quantitative morphological measurement that can be 
u sed to separate the two species. 
Table 1: Results of stepwise discriminant analysis 
Variable F-to-remove Tolerance Variable F-to-enter Tolerance 
- -�-���--- - ---- -- --.----- -
Filament length 249.04 1 .000000 Lamina length 0 . 84 0 . 97 3 3 9 1  
Lamina width 0 . 3 6  0 . 97 7962 
Petiole length 0 . 0 1  0 . 9950 1 8  
Degree calyx i s  split 0 . 84 0 . 998467 
Peduncle length 0.04 0 .9 9 22 9 1 
Style length 0 . 1 3  0 .7683 3 6  
Anther length 0 .04 0 . 8806 1 8  
Corolla width 0 . 1 1  0 . 900049 
Corolla length 0 .46 0 . 93 0 807 
98 % of the speCImens are classified correctly usmg the single variant discriminant 
function (Table 2). One individual of M. forsteri was incorrectly classified as M venosa. 
This illustrates that there is some degree of overlap between the two species. 
Table 2:  lack-knifed classification matrix. 
M. forsteri M. venosa % correct 
............................................... (�f.!��!) ................... .{�I£!���L ............................................ . 
M forsteri 53 I 98 
(Ilredicted) 
M. venosa 
(predicted) 
o 
53 
10 1 00 
1 1  
B oxplots were graphed to examine the distributions of the quantitative traits that were 
u sed in the discriminant analysis (Fig. 3 ) .  The distributions of the filament lengths do not 
93 
overlap for the two species, but the longest M forsteri filament is close to the shortest 
M venosa filament (Fig. 3 ) .  All the other distribution ranges overlap when comparing 
the two species (Fig. 3) .  M. venosa always has higher medians within the floral 
measurements and lower medians within the leaf size measurements than M forsteri 
(Fig. 3 ) .  These results show generally continuous distributions for those quantitative 
traits measured for this study. 
St igma type and fi lament attachment posit ion 
B oth clavate and capitate stigma types were observed on specimens of b oth species 
(Appendix 6) .  
Filaments were generally attached below the scales in M. forsteri except for two cases in 
which filament attachment was at the scales. The filaments of M venosa were more 
usually attached at the level of the scales, and less often below the scales (Appendix 6). 
Autofert i l ity experiments: seed set resu lts for caged and open pol l inated plants. 
M forsteri sets consistently high levels of seed whether or not pollinators are excluded. 
These results show that M forsteri does not depend on pollinators for seed production 
and is never pollen limited. M venosa sets very low levels of seed when pollinators are 
excluded, and sets considerably lower seed in unmanipulated conditions than M forsteri. 
These results show M. venosa depends on pollinators for seed production and is 
sensitive to pollen limitation (Table 3) .  
Geographic variation 
Figures 4 and 5 show leaf and flower sizes as they vary geographically. Note that leaf 
and flower sizes vary considerable at different sites, but generally they vary 
independently of each other (Fig. 4 and Fig. 5 ) .  However, adj acent populations of !vi 
venosa and M. forsteri tend to share leaf size (note the large leaves in the southern North 
I sland, and small sizes in Nelson) . 
Table 3: Mean seed set/flower (maximum 4) in open conditions (control) and with pollinators excluded. 
The range of herkogamy measurements with means is presented. 
94 
2.5 
I 2.0 · 
£ 
f 1 .5 
� 1 . 0  � u::: 0.5 
0 .0 
! 0.7 
fj-
$'. 0 6  
11 
'5 � 0.5 
o 
0.4 
Species 
Myosotis forsteri 
Myosotis venosa 
M. forsteri M venosa 
M. forsferi M. venosa 
M. forsleri M. venosa 
M forsteri M venosa 
M. forsteri M. venosa 
Control Pollinator excluded Herkogamy (mm) 
3 .84 3 . 8  range -0.8  - 0 (0) 
1 .4 0 .5  range 0 .3  - 1 . 3 (0.7) 
M forster; M. venosa 
M. forsteri M. venosa 
9 ·  
M forsteri M. venosa 
M forsten M, venosB 
40 
M. forsteri M, venosa 
Figure 3: Character distribution and variation for each of the ten morphological traits 
graphed for each species. 
95 
Lam ina Length 
o 
I? ?j Q  (j; 
Lam ina Width 
o 
Figure 4 :  Lamina length and width mapped for M. forsteri (open circles) and M venosa (closed circles) . The size of the symbol  represents 
the size of the leaves. 
96 
Coro l la Length Coro l la Width 
o 
Figure 5 :  Corolla length and widths mapped for the two species, M forsteri (open circles) and M venosa (closed circles). 97 
Discussion 
These results are consistent with the initial view of Robertson ( 1 989) that these species 
are vegetatively indistinguishable. With the exception of filament length, none of the 
floral characters measured have distinct dimensions with which to classifY these species. 
Even filament length was unable to discriminate 1 00% of the cases correctly. 
However the effect that the filament length has on the pollination requirements of these 
two species is considerable, in that it determines what degree of self-pollination may 
occur and whether or not reproduction is assured. This study showed the plants in the 
Cobb Valley population of M forsteri have the same delayed selfing mode of fertilisation 
as Robertson and Lloyd ( 1 99 1 )  described. These plants reproduce by a mixture of cross 
and self-pollinations. Plants are able to self-pollinate autonomously after all chances for 
cross-pollination have lapsed and seed production is constantly high regardless of 
pollinator activity. The results for M venosa provided evidence for quite a different 
mating type. M venosa is always herkogamous, requires a vector to achieve good seed 
set, and is vulnerable to pollen limitation in open conditions. This is inferred from the 
data collected on other species presented in Chapter two . In this situation a vector must 
mediate fertilization, whether by cross- or self-pollination. When polIinators are scarce, 
M. venosa will b e  at a disadvantage in being unable to produce seed, while M. forsteri 
will be able to produce a consistently high number of seeds. When pollinators are 
common, M venosa may be able to produce up to the same level of seed as M. forsteri 
in the same conditions, but the seed produced by M venosa may have been d one so by a 
greater level of cross-pollination. 
Much has been written regarding the superior quality of outcrossed over selfed progeny 
(see Holsinger, 1 996). In general, selfing should provide reproductive benefits whenever 
the pollination environment (availability of pollinators and mates) is poor (Lloyd, 1 979). 
Levels of inbreeding depression will affect this .  However, the high and consistent seed 
production of self-fertile plants could allow for considerable selectio n  in the offspring 
without affecting demography at all (Luitjen et at. 1 998). Populations of plants with 
mixed mating systems such as M. forsteri will be at an advantage in changeable 
environments. When pollinators are absent, individuals with selfing ability will be the 
only ones contributing genes to the next generation .  When pollinators are present, the 
98  
ability to delay selfing and receive cross-pollen will improve seed quality if inbreeding 
depression is occurring. Wright ( 1 93 9) considered such a situation to be advantageous 
to populations in which reproduction is predominantly selfing. He considered occasional 
crossing could allow for effective selection by genotypes in a "continuously restored field 
of variability" (Wright, 1 93 9) .  The mixed mating strategy therefore allows individuals to 
reproduce in difficult circumstances but also take advantage of more favourable 
conditions should they occur. It appears that M jorsteri has the advantage of being able 
to set seed in all conditions. 
Theoretical models suggest that pollination biology may play an important role in mating 
system evolution (Holsinger, 1 99 1 ) . The increased quantity of seed production that 
selfing assures and the increased quality of the seed production that crossing potentially 
delivers are opposing forces which act at different levels on individuals and populations 
in different ecological circumstances (Lloyd, 1 979). These circumstances will be  unique 
to each individual and population. In particular, pollinator abundance is expected to 
have considerable influence over selection for self-pollination when some level of 
reproduction is required for population p ersistence. Pollinators were found to be less 
abundant and less dependable when self-pollinating populations were compared with out­
crossing populations of Clarkia xantiana (F austo et al. 200 1 ) . 
An important outcome of the evolution of autogamy is  the associated development of 
reproductive isolation. When pollinators become scarce, individuals with selfing ability 
will become reproductively isolated from others within their own populations and from 
other populations. This process splits the population into non-interbreeding groups and 
over time leads to the production of groups of essentially identical individuals. The 
switch to selfing would also switch selection from individuals to genotypes, with less 
adaptive combinations being displaced by the most adaptive ones until just one clone per 
ecological niche exists (Wright, 1 939) .  If we consider M jorsteri, with the delayed 
selfing syndrome, pollinator activity will determine what degree of reproductive isolation 
will occur and whether individuals or genotypes are under selection. When we consider 
the effects on M venosa, pollinator activity will ultimately determine whether or not a 
p opulation will persist and selection will act at the population level. 
The generally accepted view of the direction of mating system evolution is that it will 
u sually proceed from outcrossing to selfing (Raven, 1 973 ; Lande and Schemske, 1 985) .  
99 
However, as much of the extant flora of New Zealand, including Myosotis, is thought to 
have arrived via recent long distance dispersal (e.g. Winkworth et at. 1 999; McGlone et 
al. 200 1 ), selfing is the more likely ancestral state for these taxa. Outcrossing types are 
thought to have arisen secondarily in New Zealand during subsequent speciation that has 
occurred as new environments have emerged (Lloyd, 1 980) though Lande and Schemske 
( I 98 5 )  suggest that it is difficult to evolve in this direction. Distributions may provide 
some insight into the direction of mating system evolution within this group. Geographic 
range will be  affected by pollination biology. Self-pollinating populations are more likely 
to establish than outcrossing populations (Baker, 1 955 ,  Pannell and Barrett, 1 998) .  Self­
pollinating individuals are potentially able to colonize new sites by the germination of just 
one seed . All they require for successful colonisation to occur, is to disperse into an 
environmentally suitable, unoccupied habitat. They do not require the presence of 
pollinators or conspecifics to successfully reproduce. S elf-pollinating indivKiuals are 
therefore expected to be  superior co Ionizers of pollinator- and conspecific-po or 
environments. Therefore, self-pollinating populations would b e  expected to occupy a 
wider range of sites and this will affect the geographic distribution of populations. This 
pattern has been observed within New Zealand Myosotis generally. Species with selfing 
mating types have larger range sizes than species with pollinator-requiring types (Chapter 
five) . M. forsteri and M. venosa also follow this pattern. That selfing species have wider 
geographic ranges than pollinator-requiring species adds some weight to the argument 
that selfing is the ancestral state. If they are an older lineage, they will have had more 
time to expand their range. However, it could be argued that as selfing species are 
superior colonizers, they will become more widespread than their pollinator-requiring 
ancestor, for which successful colonization hinges on more variables. This requires 
further investigation. 
Whatever the direction of evolution, self-pollinating individuals are expected to put less 
resources into their pollen production and flower size (Lloyd, 1 987) .  Although corolla 
size, anther length and style length are not useful characters to distinguish these two 
taxa, the vector-requiring M venosa tends to have larger values for these traits than M. 
forsteri. This trend was also shown for selfing versus non-selfing taxa in Robertson and 
Lloyd ( 1 99 1 ) . 
Stigma type did not divide the species at all . Further study of this character is required,  
however, preliminary observations suggest the shape of the stigma may be an artefact of 
1 00 
the drying and pressing process associated with the preparation of herbarium specimens. 
The continuous variation observed in filament, style and anther lengths and corolla sizes 
shows that there is a lot of phenotypic variation within each taxon. Finding geographic 
dines in vegetative traits that are independent o f  breeding system along with the 
continuous variation observed in floral characters, lends some strength to the proposition 
that this species pair may be switching between the two breeding systems. This will be 
primarily influenced by pollinator abundance at specific sites. In areas where pollinators 
are scarce the individuals with the ability to self-fertilize will be the only ones producing 
offspring and could quickly become the dominant morphological type in the population. 
It is unusual to see these two taxa growing together but it is not unknown. There are 
collections of M venosa that were found "growing with M. forsteri" (CHR 1 90975 ;  
e HR  2 1 9277) . 
It would be interesting to assess how much of the observed phenotypic variation in floral 
traits has a heritable basis that may respond to natural selection. Future studies could 
examine this in detail. 
The only morphological character that distinguishes this pair of species is filament length, 
which in turn determines the level of autonomous selfing that can occur. Such variability 
in auto fertility has not been considered enough of a distinction to support species status 
in other taxa. Luijten et al. ( 1 999) found such variation in Gentianella germanica in 
three populations studied. They also found that the average herkogamy exhibited by 
flowers in one of their study populations had changed from being positive in 1 992 to 
being negative in 1 998 (Luijten et al. 1 999). In Arenaria un?flora there are large­
flowered protandrous populations and small-flowered autonomously selfing populations 
(Fishman and Wyatt, 1 999). On the other hand, outcrossing populations of Clarkia 
xantiana have been awarded subspecies status (subsp. xantiana), as they are considered 
distinct from autonomously selfing populations (subsp . parviflora) . 
The fact that these two taxa are indistinguishable without flowers, leads me to believe 
that they are more closely related to each other than any other species of Myosotis. 
Therefore, I conclude that the degree of anther exertion in relation to the scales is not an 
appropriate character for the initial division of the New Zealand taxa, as it separates 
those species that are most closely related to each other and groups together tho se that 
1 0 1  
are less closely related. 
1 02 
CHAPTER SEVEN 
Conclusion 
The preservation of biological diversity depends o n  maintaining self-sustaining, viable 
populations of all those species that remain on this planet. The focus for achieving this 
goal is at those species that are threatened with extinction. A general rule of thumb 
predicts that rarity will precede extinction. While there has been a recent increase in 
rarity studies our knowledge of rare plant biology and population dynamics i s  still 
inadequate (Gaston, 1 994). There are several different types of rarity and not all rare 
species are threatened. The scale of the problem is such that conservation management 
of rare plant p opulations must invariably proceed on less that ideal knowledge of the 
species in question. Therefore, any improvement in our knowledge of specific rare plant 
biology will assist in the preservation of our biodiversity. 
The results of these studies have increased our knowledge of specific taxa of New 
Zealand Myosotis. Recurrent patterns have emerged such that they can be extrapolated 
to infer similar conclusions for other biologically similar species within the genus. This 
increase in knowledge regarding the biology of specific rare taxa improves our general 
knowledge of rarity in Myosotis and improves our overall understanding of rare plants 
generally. 
This thesis has improved the level of pollination biology knowledge in the genus by 
expanding on the work of Robertson ( 1 989) .  In particular, we now know for certain 
that pollinators are required for the brush blossom taxa (Chapter two). A simple 
measurement of herkogamy in the field can assist in determining the pollination 
requirements for other species in this genus. 
Pollinator -requiring taxa typically occur III larger, denser populations than non­
pollinator-requiring taxa. Examining the level of variation in seed set under natural 
conditions for those taxa that required pollinators, found much of this variation was due 
to local flower density (Chapter three). These plants were pollen limited in low-density 
patches. With as many as 33% of the New Zealand taxa considered threatened in some 
way (de Lange et al. 1 999) this has implications for conservation management. 
1 03 
P ollinator behaviour will be  influencing this process. Population management will be  
enhanced by knowledge of  the pollination requirements of  the species. Threat 
assessments will be aided by knowledge of pollination requirements, as the risks 
associated with low-density, small population sizes are not there for self-pollinating taxa. 
Hand pollinations may be required to get seed production in ex-situ collections if the 
species cannot autonomously self-pollinate. If management is in situ, population 
enhancements may be required to improve seed production, to maintain self-sustaining 
populations. We need to understand pollinator behaviour in order to advance our 
knowledge of Allee effects. 
The precocious bud pollination found in Dun Mountain populations of M. monroi is an 
interesting and previously unstudied phenomenon .  This characteristic effectively 
l engthens the initial female-only phase for this species thereby increasing chances for 
cross-pollination to occur in extreme conditions where the flowering period is very short. 
This type of stigma presentation is otherwise not known in the genus and has not been 
reported for any other species worldwide. 
The New Zealand-wide study into how rarity relates to species characteristics makes the 
connection that, typically, the species with different pollination requirements have 
different forms of rarity. Locally dense, geographically restricted taxa are pollinator 
requiring while sparse, widespread taxa are selfing. Cases that break this general rule 
may be used to identifY species at risk. 
The species complex of M forsteri and M venosa study is useful in that it identifies a 
maj or problem with the current taxonomic treatment of the New Zealand species of the 
genus. The initial division using relative anther exertion splits the most closely related 
species apart and groups them with less closely related taxa. It also suggests that 
breeding system may be unstable and subject to flux. 
In conclusion, the increase in knowledge regarding specific taxa has provided a much­
needed boost to our understanding of the population dynamics of these rare species, 
which ultimately can be used in conservation management for those taxa considered at 
risk of extinction. It can assist in the protection of populations that are not threatened in 
such a way that they do not become threatened and it can direct efforts towards the more 
pressing problem situations. It has also highlighted one of the significant problems with 
1 04 
the current classification system. 
1 05 
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1 1 6 
Appendix 1 
A report for: 
Attention: 
Under Contract: 
Nelson Myosotis 
The Conservator 
Department of Conservation 
N elson/Marlborough Conservancy 
Nelson 
Technical Support Officer (Nelson Threatened Plants) 
NELCO- 1 2554 
June, 2000 
Andrea Brandon 
Ecology Group 
Institute of Natural Resources 
Massey University 
Private Bag 1 1 -222 
Palmerston North 
06 3 5 6 9099 
A.M.Brandon@massey.ac. nz 
1 1 7 
Abstract 
The current taxonomic status of all native Myosotis in the Nelson region is  presented. There are 1 8  
distinctive taxa in the region. Factors that threaten population viability of all species are assessed. 
Species limits in the Myosotis forsteri / venosa complex are delineated. These species differ only in 
one respect; that of filament length. Species limits in the M brockiei complex are discussed. M 
'gorge creek' falls within the species description of M brockiei. M 'otuhie' falls just outside the 
limits of M brockiei in that it has different shaped corolla lobes and a wider corolla tube. 
Pollination syndromes of selected species were studied. These species fall into either one of two 
pollination syndromes based on the degree of herkogamy (spatial separation of stigma and anther 
presentation) exhibited by the flowers. Results of pollination experiments showed all species are 
self-compatible but differ in their ability to set seed autonomously. Those that could not set seed 
without a vector (non-autonomous) were all found to set variable amounts of seed in natlual 
conditions .  For these plants local density had strong effects on seed set and plants were always 
pollen limited in low-density patches. Those that could set seed without vectors of any sort 
(autonomous)  were found to set consistently high levels of seed, local density had no effect on seed 
set and plants were never pollen limited. These results have implications for the conservation of 
threatened Myosotis species as knowledge of pollination syndrome and density dependent 
reproduction can be used to determine suitable management strategies. Rarity patterns in the genus 
are linked to reproductive biology, as density dependent reproduction is likely to influence both 
population structlue and size of existing populations, while eliminating those populations too small 
to attract pollinators . 
1 .  INTRODUCTION 
1 . 1  The genus Myosotis 
The forget-me-not Myosotis is a cosmopolitan genus of the Boraginaceae and has a worldwide 
temperate distribution. Current references for the total number of species are inaccurate. Mabberly 
( 1 987) puts the worldwide distribution at 50 with 4 1  of these occurring in Europe. However, there 
are 34 New Zealand species described in the Flora of New Zealand (Allan, 1 96 1 ), although Webb et 
al. ( 1 990) put the number of New Zealand species at 47 and the worldwide total at about 1 00 .  The 
New Zealand total may still increase as the numerous tag named taxa are given taxonomic treatment. 
Druce ( 1 993) puts the New Zealand total at about 60 species, making Myosotis one of this country's 
largest p lant genera. New Zealand is the Southern Hemisphere centre of diversity for a distinct 
austral group of species (Grau and Schwab, 1 985 ;  Winkworth et al. 1 999) .  In addition to the New 
1 1 8 
Zealand taxa the austral group contains four other species; two in Australia, one in South America 
and one in New Guinea. 
1 .2 Rarity and the New Zealand taxa 
Within the New Zealand group there are a large number of extremely localised taxa, which are often 
restricted to a single mountain or range, and the genus contains some very rare species .  By contrast, 
other species have very sparse distributions and although they are relatively widespread, they are 
never common where they occur. Several different abundance and distribution patterns or rarity 
patterns are evident within the New Zealand taxa. For example Myosotis forsteri is found within 
about three quarters of New Zealand's land area south of latitude 3 8° S (Landeare Research 
Herbarium, Lincoln, hereafter referred to as CHR; Allan, 1 96 1 ) .  While having a widespread 
distribution, it is often found as a single individual or as two or three plants in a population and has 
only occasionally been seen in populations as large as 30.  Although never common where it occurs, 
it is not considered threatened in any way. By contrast, M concinna, an endemic of the Marino 
Mountains in north-west Nelson, occurs in a very restricted geographic area. Although confined to 
specific habitats within the alpine zone, it is quite common where it occurs .  
Species can be rare in  different ways and for many reasons. Aspects of  reproductive biology have 
been linked to rarity in several studies (e.g. Rabinowitz, 1 978 ;  Oakwood et al. 1 993 ,  Quinn et al. 
1 994; Kunin and Shmida, 1 997). Breeding system, pollination ecology, dispersal ability and 
vegetative reproduction are important factors in deternlining plant distributions. For example, self­
pollinators can grow, reproduce and colonize a new area by the germination of just one seed. They 
can reproduce in isolation and do not require the presence of others to persist. Therefore small 
population size is not necessarily a sign that a population of such a species is threatened. Obligate 
outcrossers or self-incompatible plants require local population densities at levels that attract vectors 
and ensure a supply of cross pollen to achieve pollination. Therefore, to be successful, they may 
need population sizes that are considerably larger than those required for selfing species and a small 
population size could be a threat to viability. Other factors, such as environmental constraints, and 
the evolutionary and recent history of populations will affect abundance and place limits on 
distributions . IdentifYing the factors involved in maintaining the distribution patterns observed will 
assist in understanding the vulnerability of small populations . 
The state of rarity can be used to describe several different patterns of density and distribution. 
Rarity is  defined s imply by Gaston ( 1994) 'as the state of having low abundance and/or a small 
range size' . Some authors have attempted to define rarity by categorising it, as a temporal and/or 
spatial phenomenon (e.g. Rabinowitz, 1 98 1 ;  Fiedler and Ahouse, 1 992). Others have focused on 
evolutionary history (relictual versus incipient e.g. Prober et al. 1 990), genetics (e.g. Hamrick et al. 
1 1 9 
1 99 1 ), or conservation priority (e.g. Dopson et al. 1 999) . de Lange and Norton ( 1998) addressed 
the inconsistency in both the meaning and usage of the term rarity as it relates to our threatened 
p lants and proposed revised risk categories that took this into account. In particular, the new 
system, which has now been adopted by the New Zealand threatened plant committee and used for 
the recent reappraisal (de Lange et al. 1 999), attempts to separate rarity from threat. 
1 . 3  Threatened Myosotis 
A large proportion of the New Zealand taxa in the genus are considered threatened, with 3 3% 
featuring on  the latest list (de Lange et  al. 1 999), but are often not well enough known in  the field or 
are of uncertain taxonomic status (Molloy and Davis, 1 994; Cameron et al. 1 995). Priority setting 
and management decisions for their conservation are impeded by this lack of knowledge. Six of the 
Nelson taxa are currently listed as threatened in some way. M laeta has been classified as 
Vulnerable (Cameron et al. 1 995) but the reappraisal to the newly erected Range Restricted category 
(de Lange et al. 1 999) acknowledges recent survey results; M hrockiei has been classified as Rare 
(Cameron et al. 1 995), I (Insufficiently known) (Dopson et al. 1 999) and is now classified as Range 
Restricted (de Lange et al. 1 999); M. angustata, M arnoldii and M concinna were on the local 
plant list (Cameron et al. 1 995) and are now classified as Range Restricted (de Lange et al. 1 999). 
M petiolata var. petiolata has been classified as Insufficiently Known since 1 993 (Cameron et al. 
1 993 ;  Molloy and Davis, 1 994; Cameron et al. 1 995; de Lange et al. 1 999). 
1 .4 Taxonomic problems 
Numerous tag-named taxa have arisen over the years and there is little doubt that a full revision of 
the austral group of the genus is overdue. Their rarity has contributed to the taxonomic difficulties 
as they are seldom seen in the field and are simply not that well known. New Zealand Myosoti.y is 
now thought to be of very recent speciation history (Winkworth et al. 1 999). This may be a causal 
factor as speciation may be so recent that incipient taxa have not yet experienced full population 
expansion nor dispersed into all potential habitats . The species is an evolutionary concept (Harvey, 
1 996) but at any point in time we are looking at a ' snapshot' of the evolutionary process, where for 
some taxa, boundaries may be vague and ineonsistent across the range of forms while for others 
species limits may be clearly evident. 
A lot of the taxonomic difficulties have arisen within selfing taxa. For each individual in a selfing 
population, reproduction is usually uniparental, therefore there is little chance for any gene flow 
from within their own population much less another population. Each plant is  essentially 
reproductively isolated from any other. Under these circumstances even when chance occurrences 
for pollinator-mediated pollen transfer between local flowers does take place, the close familial 
1 20 
relationship between plants in the same population will be unlikely to confer any new genetic 
material to their progeny (i .e .  inbreeding limits the effectiveness of meiosis) .  This results in races 
being formed, where in a single population, all individuals may be genetically identical, and the lack 
of any recombination between unrelated individuals results in reduced variability within that 
particular population. 
2. NELSON TAXA 
The genus is  well represented in the Nelson region by rare but well described species as well as taxa 
whose affinities in the genus are not well understood. The Nelson area contains 20 named taxa 
(Allan, 1 96 1 ;  Moore and Simpson, 1 973;  CHR), with an additional 7 tag-named taxa (Druce, 1 993 ;  
Courtney, pers .  cornrn.). Of these, Myosotts 'gorge creek' , M. 'otuhie' , M. 'paynes ford' , M ' cundy 
creek' and M ' flora' were unusual forms that were difficult to place into species and required 
taxonomic interpretation. The other tag-named taxa are in the M australis aggregation; M 
australis 'small white ' , M australis ' calcareous white' and M australis 'yellow' (Druce, 1 993) .  
2 . 1 Myosotis forsteri / venosa complex 
The highly variable M .ftJrsteri aggregation is a self-pollinating taxon with many morphological 
forms. Small differences are often found among populations of this species .  M /orsteri has an 
initial stage when stigmas are receptive and pollination can occur prior to anther dehiscence, 
allowing some chance for outcrossing (Robertson and Lloyd, 1 99 1 ) .  This is variable among 
populations, which is reflected in the morphological variation seen in the field. 
The first key in the current treatment by Moore (in Allan, 1 96 1 )  follows the traditional pattern of 
sub-generic classification of the genus by separating species on the basis of degree of anther exertion 
into two sections .  This trait has proved to be difficult to use to identify taxa as there are 
intermediate forms that make division arbitrary. Moore admitted, "though the position of the anthers 
in relation to corolla scales is used in the first division of the key below, there is no firm conviction 
that this leads to the most nearly natural arrangement" (p 807:  Allan, 1 96 1 ) .  It is thought that this 
method of classification led to recognition of species on the basis of relative anther exertions that 
could not be differentiated any other way (Robertson, 1 989). In the case of Myosoti.'" forsteri Moore 
notes that "plants . . .  collected . . .  on many North Id. mountains, (the) relative lengths of filaments, of 
anthers and of styles vary . . .  tending to bridge the gap between this species and M venosa" (p 822). 
Of M venosa Moore notes, "This species . . .  more closely resembles M forsteri. Without the 
corolla and stamens specimens can be determined only tentatively by the slightly finer and more 
spreading hairs and the long style with clavate stigma" (p 823 : Allan, 1 96 1 ) .  
1 2 ] 
In order to gain a little more insight into how such differences affect species limits, a detailed study 
of M forsteri and M venosa was carried out. The difference in leaf hair and stigma type varied 
within the specimens studied in a manner that reflects regional rather than specific variation. These 
species cannot be distinguished without flowers being present on specimens .  These two taxa differ 
in only one dimension; that of filament length, which determines the extent of anther exertion. The 
major difference anther exertion makes to an individual is whether or not they are able to self­
pollinate. As there are several of these species complexes in the New Zealand group, taxonomic 
decisions regarding this s ituation will have to be made when the genus is revised as a whole .  For 
now, these taxa will remain treated as separate entities . 
2 . 2  Myosotis brockiei complex 
Populations of M brockiei vary considerably in habit, l eaf shape and leaf hairiness. These 
differences occur among populations at the Cobb Reservoir, all growing on the same geological 
substrate but also occur between populations of those plants and those on the limestone outcrops.  
The old Magnesite Quarry at the Cobb Reservoir has a population of plants that have a relatively 
sparse covering of more or less appressed hairs on their rosette leaves .  These plants have a narrow 
petiole that tapers gradually from an elongated, elliptic lamina and plants are often growing as single 
rosettes .  More typical plants, which can be found nearby in the Cobb Gorge below the quarry, have 
crowded, spreading leaf hairs that give the leaves a velutinous texture. Plants found on the limestone 
outcrops have leaves with similar texture, but they are larger, more robust leaves ,  with less well 
defines petioles than the Cobb reservoir ones .  They usually eonsist of several roscttes. 
Plants were collected and grown on to determine whether tag-named entities M 'gorge creek' and M 
'otuhie '  were distinctive from M brockiei. M. 'gorge creek' was found to fall within the species 
description of M brockiei (Moore and Simpson, 1 973) which widens that species known geographic 
and altitudinal range. 
M ' otuhie' on the other hand has a couple of distinctive traits that place it just outside the 
description of M brockiei (in Moore and Simpson, 1 973) .  Differences are in the shape of the 
corolla lobes, which are rounded rather than ovate and have a wider corolla tube (�2mm diameter). 
The general habit is unusual for M brockiei, however, III that plants form very large mats with many 
more rosettes than typically seen. The habitat in which these plants are found has been modified for 
sheep and dry stock farming. The largest matted plants seen are well within browse level and may 
have been unnaturally "cropped" into a more vegetatively reproducing type of plant. Other plants 
observed are hanging from limestone cliffs above the level of browse but these may be atypical 
1 22 
forms that were able to survive in refugia. The multicipital habit is in Moore and S impson's  ( 1 973) 
description. 
2 .3  Other problem taxa 
The M pygmaea complex is a self-pollinating group in which there are four named varieties and 
additional tag-named taxa, such as the threatened M 'volcanic plateau ' .  M p. var. pygmaea and M 
p. var. drueei and have been given variety status in the previous treatment but Druce ( 1 993) 
considered them sufficiently distinct to be species. An attempt to separate M p. var. pygmaea from 
M p. var. drueei was made at the CHR herbarium. Traits that distinguish the two taxa convincingly 
in the Nelson region using the descriptions by Moore (in Allan, 1 96 1 )  could not be used for 
specimens of other localities, where traits were unsystematically shared among those specimens seen 
(Robertson, pers. corum.) .  
Myosotis teneri eau lis and spathulata are difficult to separate on the basis of vegetative characters 
alone for tlle sanle reason . They have both been studied and were found to self-pollinate (Brandon 
and Robertson, in prep (b); Robertson and Lloyd, 1 99 1 ) . They can be discriminated, using the 
treatment by Moore (in Allan, 1 96 1 ), on the degree of anther exertion. In M teneri eau lis, anthers 
are completely included inside the corolla tube, in M spathulata, they are exerted at least partly 
above corolla scales and can be carried as far as halfway up the corolla lobes. Plants whose anthers 
are exerted beyond the halfway point then become M matthewsii .  However, this i s  a continuum, 
which does not enable clear-cut boundaries to delineate the limit of each species. In addition, in the 
Nelson region, the vegetative features of one species can be found with the flower type of the other. 
As these taxa cannot be reliably distinguished they are treated together in this report. 
A set of collections that are curious are those of M matthewsii which otherwise is known only from 
Northland . These collections were examined at the CHR herbarium, and were found to be 
misidentified M spathulata / teneri eau lis. 
M. elderi is thought to be synonymous with M. lyallii var. lyallii as is M lyallii var. townsonii 
(Robertson, 1 989; Druce, 1 993) .  Filament length distinguishes M lyallii from M elderi. Unlike the 
Jorsteri / venosa complex, style length is variable in M elderi which provides this taxon with a 
mixed pollination system without filament length variability. As the filament length variation does 
not separate a selfing from a non-selfing taxon there is not such a dramatic dividing line that can be 
used to delineate individuals on the basis of pollination syndrome. M. lyallii var. lyallii and var. 
townsonii were considered distinct varieties by Moore in Allan, ( 1 96 1 )  due to differences in the 
calyx hairs and lobes. At that time, they were only known from disjunct locations in the South 
Island. However, more collections have since been made, and their distributions are now much wider 
1 23 
with both taxa occurring in the Nelson mountains.  It seems unlikely that these two taxa are distinct 
enough to be considered varieties. 
These types of problem do not arise as frequently in the vector-requiring species that occur in the 
area. For example, M monroi is quite uniform morphologically throughout its range of populations 
at Dun Mountain. Plants at the Red Hills Ridge and Porters Ridge populations are also uniform at 
those sites. There are, however, small differences in rosette leaf morphology between the two 
disjunct sites. M arnoldii plants differ between Hoary Head and Chalk Range populations in one 
respect, the hooked hairs on the calyces of Marlborough plants are absent on Nelson plants. In taxa 
that require vectors to reproduce, gene flow is occurring to some extent between individuals ,  and due 
to a far greater degree of shared genetic material, individuals are much more uniform within their 
populations . As soon as a barrier to gene flow is present, which can be due to self-pollination or 
geographic separation, differences start to appear between populations. 
1 24 
2.4 Summary 
The table below lists the taxa known to occur in the Nelson area, including the tag-named entities 
along with their perceived distinctiveness in the region. 
Table 1 :  Summary of Nelson taxa including all tag-named entities with their taxonomic status 
Taxon Taxonomic status 
1 .  M. elderi L.  B .  Moore Synonymy with M lyalli i 
2 .  M. tenericaulis Petrie Difficult to distinguish from M. spathulata 
3 .  A1. pygmaea Col. var. pygmaea Distinctive taxon in N.W. Nelson 
4 .  M. pygmaea Col. var. drucei L. B .  Moore Distinctive taxon in N. W. Nelson 
5 .  M. traversii Hook. f. var. traversii Species 
6 .  lvi. jorsteri Lehm. Species 
7 .  M. venosa Col . Species 
8 .  M. laeta Cheesem. Species 
9 .  1'v1. petio/ata Hook. f. var. petiolata Species 
10.  lvi. monroi Cheesem. Species 
1 1. A1. concinna Cheesem. Species 
1 2 .  lvi. macrantha (Hook. f.) Benth. Et Hook. f. Species 
1 3 .  ]v!. arnoldii L .  B .  Moore Species 
1 4. lvi. angustata Cheesem. Species 
1 5 . A1. lyallii Hook. f. var. Zvallii Synonymy with M elderi 
1 6 .  1Vi. lyallii Hook. f. var. townsonii Synonymy with M lyallii 
1 7 .  A1. spathulata Forst. f. var. spathu/ata Difficult to distinguish from M. tenericaulis 
1 8 . M. matthewsii L. B .  Moore These specimens have been mis-identified, they are in the M 
spathulata / tenericaulis complex 
1 9. M. brockiei Species 
20 .  A1. 'otuhie' Distinctive taxon; var. of M. brockiei 
2 l .  M 'gorge creek' Ai. brockiei 
22.  A1. 'cundy creek' One form of the variable M. jorsteri aggregation. 
23 .  N!. ' l1ora' No such entity 
24. A1. 'paynes ford' M. spathulataitenericaulis - spathulata leaves, tenericaulis  fio\' 
25 .  A1. australis R .  Br .  'yellow' Distinct taxon 
26. N! a. 'small white' Distinct taxon 
27. Ad. a. 'calcareous white' Synonymy with 'small white' 
1 25 
2 .5  Checkl i st of Nelson taxa 
The table below lists the distinctive taxa ill the regIon, their current conservation status and 
recommendations where considered appropriate. 
Table 2: Distinctive Nelson taxa 
Taxon Current conservation status Recommendations 
M. rnonroi Category I, removal recommended (Dopson et Ok 
al. 1 999) 
lvi. rnacrantha None Ok 
M. laeta Range restricted (de Lange et al. 1 999) Vulnerable; small range size, 
Category B recommended (Dopson et al. 1 999) small number of populations 
known, habitat invasion by 
manuka into large population site 
;\;f. brockiei Range Restricted (de Lange et al. 1 999) Range Restricted 
Category I, medium priority CDopson et al. 
1 999) 
Af 'otuhie ' None Vulnerable; small geographic 
range, small number of plants 
known, modified habitat, lack of 
legal land protection 
lvf. tenericaulis/spathulata None Ok 
;\;f. forsteri None Ok 
A1. venosa None Ok 
j\;f. petiolata var. petiolata Insufficiently Known (de Lange et al. 1 999) Endangered, small population 
Category I, high priority (Dopson et al. 1 999) sizes, only 2 populations known, 
tiny range size 
lw. arnoldii Range Restricted (de Lange et al. 1 9 99) Range restricted 
1'1/f. angustata Range Restricted (de Lange et al. 1 999) Vulnerable, small populations, 
not many populations known, 
small range size 
M. concinna Range restricted (de Lange et al. 1 9 99) Range restricted r I 
M. Zvallii/elderi None Ok I 
Nf. traversii vaT. traversii None Ok 
M. pygrnaea var. drucei None Ok 
M. pygrnaea vaT. pygrnaea None Ok 
M. australis 'yellow' None Ok 
r 
M. australis 'small white' None Ok 
1 26 
3. Reproductive biology in  New Zealand Myosotis 
3. 1 Glossary of terms 
Dichogamy: 
Protogyny: 
Herkogamy: 
Allee effects : 
temporal separation of stigma and anther presentation 
the form of dichogamy in which stigma presentation precedes anther presentation 
(opposite of protandry) 
spatial separation of stigma and anther presentation 
Inverse density-dependent effects that occur when a component of individual 
fitness (e.g. rate of reproduction) decreases disproportionately in response to a 
decrease in population density or size (Allee, 1 95 1 )  
Tube blossom: These flowers usually have a narrow corolla tube of variable length. The tube is 
framed by conspicuous corolla scales, with flat, free corolla lobes (fig I ) .  
Filaments are more or less short carrying anthers near the top of  the tube, but the 
degree of inclusion! exertion varies . 
Funnel blossom: These flowers have a wider corolla tube that is more or less funnel shaped. The 
corolla lobes are spreading rather than flat and often fused above the scales giving 
the flower a funnel shape (fig 2) .  
Brush blossom: These flowers have a narrow corolla tube, with a rim of conspicuous scales and 
free flat corolla lobes, but differ from the tube blossom type in having anthers and 
stigma on long exerted filaments and styles (fig 3 ) .  
Fig 1 .  M. traversii var. traversii (BS) Fig 2 .  M. arnoldii (BM) Fig 3 .  M. brockiei (AWR) 
1 27 
3 .2  The general condit ion 
New Zealand Myosotis species studied in detail have been found to have different pollination 
syndromes that depend, in part, upon the degree of anther exertion displayed and length of the style 
in relation to the position of the anthers (Robertson and Lloyd, 1 99 1 ) . Moore (in Allan, 1 96 1 )  states 
that " . . .  exserted anthers are little known in the genus outside NZ". The general character of the 
genus here differs in many respects from the Northern Hemisphere relatives .  Several aspects of the 
reproductive biology of selected taxa have been studied. All species studied so far have been found 
to be fully self-compatible, but differ in their ability to set seed autonomously (Robertson, 1 989; 
Brandon, unpubL).  With the exception of M pygmaea vac minutiflora, which was not 
dichogamous, all species studied to date have incomplete dichogamy in thc form of protogyny 
(Robertson and Lloyd, 1 99 1 ;  Brandon and Robertson, in prep (a)) .  Allee effects in reproductive 
effort were found in four vector-requiring species of Myosotis (Brandon and Robertson, in prep (b» , 
Some species have precocious buds (sensu Robertson, 1 989), in which stigmas are exerted before 
the bud opens . Pollination of precocious buds occurs in Myosotis monroi (Brandon, in prep ,). 
Hcrkogamy measurements indicate some species employ mixed pollination syndromes within 
populations . 
3 .3  Summary of manuscripts i n  preparation 
3. 3. 1 Pol l i nation syndrome, herkogamy and rar ity i n  s ix species of New Zealand 
Myosotis 
The reproductive b iology of six species of Myosotis was studied. New Zealand Myosotis species 
studied to date fall  into either onc of two pollination syndromes based on the degree of herkogamy 
exhibited by the flowers, Details of the pollination syndromes operating in six species of Myosotis 
are presented. Hand pollination tests showed all six species are fully self-compatible, The four 
species with brush or funnel blossom flowers, Myosotis monroi, M brockiei, M laeta and M 
macrantha, require pollinators to transfer pollen and set seed. The two tube blossom species, M 
jorsteri and M spathulata / tenericaulis are able to set seed without pollinators and arc therefore 
autonomous .  These pollination syndromes are directly related to the degree ofherkogamy displayed. 
Pollen limitation was found to occur in the four pollinator-requiring species but not in the two 
autonomous species , Not all tube blossom species are autonomous ,  Robertson ( 1 989) found two 
tube blossom species, M colensoi and M un�flora, require pollinators . The association between 
1 28 
pollination syndromes and rarity patterns are discussed. The breakdown ill dichogamy and 
herkogamy are linked to the evolution of autogamy. 
3 .3 .2  Al lee effects i n  plant reproductive performance: Local density, popu lat ion size, 
rarity and reproductive success in  natura l  populations of Myosotis L. 
(Boraginaceae) 
Reproductive failure due to Allee effects is a possible consequence of low population density and 
small population size for plants . Data were col lected from natural populations of five species of 
Myosotis L. (Boraginaceae) with different pollination requirements and rarity patterns in the Nelson 
region of New Zealand. Seed set per flower was measured in populations of varying density and 
size. For pollinator-requiring species, Myosotis monroi, M macrantha, M laeta and M brockiei, 
local population density had strong effects on seed set, while population size had no effect. These 
plants were always pollen limited in low density patches. For a self-fertile species, M jorsteri, seed 
set was always high and unaffected by either local density or population size and pollen was never 
limiting. These results indicate reproductive success in pollinator-requiring species of Myosotis is 
subject to Allee effects and these effects occur at a very local scale. This density-dependent process 
can eJo..rplain how the different patterns of density and distribution observed are maintained for each 
species. These results have implications for the assessment and management of threatened Myosotis 
species in particular and rare plants generally. It is essential to know the pollination requirements 
and levels of density dependence for reproduction both for the assessment of threat and for 
detennining management strategies for rare plants. Species that are able to self-pollinate are not 
affected by the presence of conspecifics and will not necessarily be at risk if found at low density. 
Species that suffer Allee effects will be more susceptible to local population extinction when 
densities fall below a critical threshold. Identifying density dependence and determining critical 
thresholds of density below which reproductive success is affected should be an important 
component of rare plant conservation. 
3 .3 .3  Precocious bud pol l i nation: Maxim izing chances for cross pol l i nat ion i n  the 
u ltramafic endemic Myosotis monroi 
M. monroi has brush blossom floral morphology (Robertson, 1 989; Brandon, unpub1 . ) .  In M 
monroi the buds open almost sinlUltaneously and the stigma presentation in the buds is precocious, 
exposing the stigma for pollination before the bud opens, which has the effect of eJo..1:ending the 
relative length of the female phase (Robertson, 1 989). In species that require a vector for pollination 
1 29 
to occur, self and cross pollen alike must be deposited via the vector (Holsinger, 1 996), so the longer 
the stigma is exposed prior to anther dehiscence, the greater the chance of outcrossing. Stigmas were 
collected from precocious and fully open flowers to determine whether pollination was taking place 
at the precocious phase. 25% of the precocious stigmata collected had received pollen, and 1 1 .6% 
had received more than 5 pollen grains . Of the brush blossom species studied so far, Myosotis 
monroi is one of the more successful taxa, which although it has been considered at risk in the past, 
is no longer regarded as threatened. Rarity patterns within the genus have been found to be affected 
by the pollination syndromes of the taxa studied (Brandon and Robertson, in prep (b» . The 
evolutionary consequences for species that employ pollination syndromes that increase the chance of 
outcrossing are discussed. 
3 .4 Reproduction and rarity 
Species that exhibit density dependent reproductive effort, such as M monroi, typically have 
clumped local densities and restricted distributions. Such density dependent processes are likely to 
influence the population dynamics of these species. Low seed production in low density patches will 
limit population growth and local extinction may eventually result at those sites. Species that do not 
exhibit density dependence in their reproductive effort, such as M pygmaea, typically have sparse 
but widespread distributions . The population dynamics of these species are not affected at all by the 
presence of conspecifics. These populations do not appear to be limited by seed production, which is  
always high. Population growth for these species is more likely limited by microsite availability. 
These typical patterns are not always observed in the field .  For instance, M. angustata has typically 
small to moderate sized populations but also a limited geographic distribution. This species was 
found to have both types of pollination syndrome operating within a single population. The presence 
of self-pollinating plants will mask any density dependent interactions that may be occurring. 
3 .5  Summary 
The table below summarizes the results from the studies conducted on reproductive biology in 
Myosotis. Inferences are made for taxa on which detailed studies were not carried out based on the 
degree of herkogamy exhibited by flowers . 
1 3 0  
Table 3: Summary of the reproductive biology of the Nelson taxa 
,Species Herkogamy Selfing Pollination Evidence of 
(mm) 
ratel syndrome density-
dependence 
M. monroi 0.7 2.8 0 .039 Non-autonomous Yes 
M. macrantha 2.8  - 5.2 0 .042 Non-autonomous Yes 
M. laeta 0.9  - 1 . 8  0 .02 Non-autonomous Yes 
M. hrockiei 2.7 - 4.9  0 .042 Non-autonomous Yes 
M. 'otuhie" 1 .5 - 3.4 - N on-autonomous2 -
M. spathulata / 0 0 .92 Autonomous No 
tenericaulis 
M·forsteri 0 0 .95 Autonomous No 
lv!. venosa 0 . 5  0 . 9  0 .04 Non-autonomous -
lv!. petiolata 2 - 5 . 1  OJ)275 Non-autonomous -
M. amoldii 2.2 7. 1 - Non-autonomous2 -
M. angustata 0-1 . 5 - Both2 -
A1. concinna 3 . 6  - 6.2 - Non-autonomous2 -
M. lyallii / elderi 0 1 4  - Both2 
M. traversii 0- 1 2  - Both2 -
A1. p. var. pygmaea 0 - Autonomous2 -
l'vl.p. var. drucei 0 - Autonomous2 -
A1. australis 'yellow' 0 - Autonomous2 -
A1. a. 'small white' 0 - Autonomous2 
I = proportion of ovules that mature into seeds per Bower when poIlinators are excluded; 2 inferred irom herkogamy measurements 
4. Acknowledgments 
Evidence of 
pollen 
limitation 
Yes 
Yes 
Yes 
Yes 
-
No 
No 
Yes 
Yes 
-
-
-
-
-
-
-
-
I wish to thank Shannel Courtney for providing indispensable technical and logistic support for this 
research. Simon Walls, Tim Shaw and Graeme Ure also provided invaluable support. I also wish to 
thank Murray Parsons, Debbie Redmond and Mary Korver of Landcare Research for their 
commitment to databasing the Myosotis collection. 
Bill Ma1colm has kindly granted pennission for reproduction of his slides of Myosotis forsteri. M 
arnoldii and M monroi. 
1 3 1 
5. References 
Allan, H.H. 1 96 1 .  Flora of New Zealand. Volume 1. P .D Hasselberg, Government Printer, 
Wellington, New Zealand. 
Allee, W.e . 1 95 1 .  The Social Life of Animals .  Beacon, Boston. 
Brandon, A M. unpubl .  Systematics and Ecology of Nelson Myosotis L. (Boraginaceae) . 
Massey University, Palmerston North. PhD Thesis .  
Brandon, AM. in prep. Precocious bud pollination: Maximizing chances for cross pollination in 
the ultramafic endemic Myosotis monroi. 
Brandon, AM. and Robertson, AW. in prep (a). Pollination syndromes, herkogamy and rarity in 
six species of New Zealand Myosotis L. (Boraginaceae). 
Brandon, AM.  and Robertson, AW. in prep (b) . Allee effects in plant reproductive performance: 
Local density, population size, rarity and reproductive success in natural populations of 
Myosotis L. (Boraginaceae) . 
Cameron, E.K. ,  P .1 .  de Lange, D.G. Given, P .N.  Johnson and e .c. Ogle, 1 993 . New Zealand 
Botanical Society Threatened and Local Plant Lists ( 1 993 Revision) . New Zealand 
Botanical Society Newsletter 32: 1 4-28 . 
Cameron, E.K. , P . 1 .  de  Lange, D. R. Given, P.N. Johnson, c.c.  Ogle, 1 995 . Threatened and 
local plant lists ( 1 995 Revision). New Zealand Botanical Society Newsletter 39: 1 5-28. 
de Lange, P.1 .  and D.A Norton, 1 998 .  Revisiting rarity : a botanical perspective on the meanings 
of rarity and the classification of New Zealand' s  uncommon plants. Royal Society (�f New 
Zealand Miscellaneous c\,'eries 48: 1 45 - 1 60. 
de Lange, P .J . ,  P .B .  Heenan, D .R. Given, D .A, Norton, e .c.  Ogle, P .N .  Johnson and E.K. 
Cameron, 1 999.  Threatened and uncommon plants of New Zealand. New Zealand 
Journal qf Botany 37: 603-628 . 
Dopson, S .R . ,  P .1 .  de Lange, e .c. Ogle, B .D .  Rance, S . P .  Courtney and 1 .  Molloy, 1 999. The 
conservation requirements of New Zealand' s  nationally threatened plants. Threatened 
species occasional publication No. 1 3 ,  Biodiversity Recovery Unit, D epartment of 
Conservation, Wellington. 
Druce, AP .  1 993 . Indigenous higher plants of New Zealand. Unpublished checklist, Landcare 
Research, Lower Hutt. 
Fiedler, P .L .  and J .1 .  Ahouse, 1 992. Hierarchies of cause :  towards understanding of rarity in 
vascular plant species .  In: P.L.  Fiedler & S.K. Jain, (eds .) Conservation biology: the 
theory and practice (if nature conservation, preservation and management, Chapman & 
Hall, New York. pp 23-48.  
Gaston, K.1 .  1 994. Rarity. Chapman and Hall, London. 
1 3 2  
Grau, 1. and A Schwab. 1982 .  Mikromerkmale der blute zur gliederung der gattung Myosotis. 
Mitt. Bot . .  Munchen 1 8: 9-58 .  
Hamrick, 1 .L . ,  MJ.W.  Godt, D.A Murawski and M.D.  Loveless, 1 99 1 .  Correlations between 
species traits and aIIozyme diversity: implications for conservation biology, pp 75-86.  In: 
D.A Falk and K.E.  Holsinger (eds.) Genetics and Conservation of Rare Plants. Oxford 
University Press, New York. 
Harvey, P .H . ,  1 996. Phylogenies for ecologists .  Journal of Animal Ecology 65 (3): 255-263 . 
Kunin, W.E. and K.1 .  Gaston, 1 993 . The biology of rarity: patterns, causes and consequences. 
Trends in Ecology and Evolution 8: 298-3 0 1 .  
Kunin, W.E. and A Shmida, 1 997. Plant reproductive traits as a function of local, regional, and 
global abundance. Conservation Biology 1 1 :  1 83 - 1 92.  
Mabberly, DJ.  1 987 .  The plant book, a portable dictionary of higher plants. Cambridge 
University Press . 
Moore, L .B .  and Simpson, MJ.A 1 973 . A new Myosotis from north-west Nelson. New 
Zealand Journal qfBotany 1 1 : 1 63 - 1 70 .  
MoIIoy, J, and Davis A, 1 994. Setting priorities for the conservation of New Zealand' s  
threatened plants and animals .  Department of Conservation. 
Oakwood, M. ,  E. Jurado, M. Leishman and Westoby, M. 1 993 . Geographic ranges of plant 
species in relation to dispersal morphology. Journal (i Biogeography 20: 563-572. 
Prober, S .M . ,  J . c .  Bell, and G. Moran. 1 990. A phylogenetic and allozyme approach to studying 
rarity in three "green ash" eucalypts (Myrtaceae). Plant Systematics and Evolution 1 72: 
99- 1 1 8 . 
Quinn, R.M.,  J .H. Lawton, B . c. Eversham, and S .N .  Wood . 1 994. The biogeography of scarce 
vascular plants in Britain with respect to habitat preference, dispersal ability and 
reproductive biology. Biological Conservation 70: 1 49- 1 5 7 .  
Rabinowitz, D.  1 978 .  Abundance and diaspore weight i n  rare and common prairie grasses. 
Oecologia 37: 2 1 3-2 1 9  
Rabinowitz, D .  1 98 1 .  Seven forms of rarity pp . 205-2 1 7  In: H. Synge (ed) The biological 
aspects qf rare plant Conservation, John Wiley & Sons, New York. 
Robertson, AW.,  1 989 .  Evolution and pollination of New Zealand Myosotis (Boraginaceae) . 
University of Canterbury, Thesis for PhD. 
Robertson, AW.,  and D . G. Lloyd. 1 99 1 .  Herkogamy, dichogamy and self-pollination in six 
species of Myosotis (Boraginaceae) . Evolutionary Trends in Plants 5 :  5 3-63 . 
Webb, C .J . ,  P .N. Johnson and B .  Sykes. 1 990. Flowering plants qf New Zealand. DSIR B otany, 
Christchurch. 
1 3 3  
Winkworth, K C, AW. Robertson, F .  Ehrendorfer, P J. Lockhart, 1 999.  The importance of 
dispersal and recent speciation in the flora of New Zealand. Journal of Biogeography 26: 
1323-1325 . 
134  
6. Appendices 
6 . 1 Explanation of fields i n  species profi les 
6. 1 . 1  Abbreviat ions 
P pollinator required 
S able to self pollinate 
DD  density dependent seed production 
6. 1 .2 Reproduct ion and recruitment 
All observations and results presented in this section are largely based on as yet unpublished data collected 
by the author during 1 996·2000 while conducting research for a PhD. 
Hcrkogamy 
Selfing rate 
Dichogamy 
Average seed sct 
6 .2  Distribut ion Maps 
spatial separation of stigma and anthers measured in  the field in  millimeters 
seed set by plants when pollinators were excluded 
proportion of time each flower spends in the female phase (i.e. receptive 
stigma) prior to anther dehiscence 
seed set/flower in open pollinated plants under natural conditions 
TI1e maps were produced using CHR collection records as  well as the author's observations over the 
period of research. Herbarium records are italicised where grid references were not supplied by the 
collector/s o In these cases, approximate grid references have been estimated b ased on the locality 
description on the sheets. 
6 .3  Photographs 
AWR 
BM 
BS 
AMB 
Alastair Robertson 
Bill Malcolm 
Bruce Sunnex 
Andrea Brandon 
1 3 5  
6.4 Species profiles 
Myosotis monroi Cheesem. 
Ranking: M. monroi was considered threatened in previous threatened plant lists (category I in Molloy and Davis 
( 1 994) and the Botanical Society Local Plant list in Cameron et al ( 1 995» . M monroi is now known to occur in very 
large populations within its range and is no longer considered threatened (Courtney, pers. comm.) which has prompted 
its removal from the threatened plant lists (de Lange et al, 1 999). 
Abundance and Distribution : M. monroi has a limited geographic  distribution, restricted to the serpentine mineral 
belt which appears sporadically along the ranges east of Nelson, from D'Urville Island (records in the National Museum 
(WELT» in the north through to the Red Hills in the south. This species has a clumped distribution, with some plants 
occurring in dense patches, while other sites, which appear to be suitable, contain no plants at all . Population sizes for 
this species are typically large. 
Habitat: non-forest, ultranlafiC, rocky pavement/fell-field, above 800 111. 
Threats: None. 
Distinguishing features: Plants usually consist of several rosettes, the leaves are often bronze, with short appressed 
hairs, which are absent undemeath. The inflorescence remains compact throughout flowering, which along with 
synchronous opening of flowers gives it an almost capitate appearance. Each plant can have several inflorescences, 
which along with the capitate cymes produce a large floral display. Flowers have a white corolla with yellow scales, 
are scented and of the brush blossom type. 
Plants are similar to M laeta, but distinguishable by the absence of hairs on the underside of rosette leaves in the latter 
and inflorescence type, which in Iv! laeta elongates over the reproductive season and flowers open sequentially rather 
than synchronously. Plants are distinguishable from M. macrantha in that the rosette leaves are greener i n  the latter, but 
the main difference is in flowers, which in M macrantha are variably coloured but never white. Plants can be 
distinguished from M. angustata by the rosette leaves which in the latter are very narrow, greenlblue in colour and when 
flowering material is present, by the length of the filaments, which in M angustata are short. 
Rep" oduction and recruitment: Study site: Dun Mountain. Results: herkogamy: 0 .7 - 2.8 mm; selfing rate: 0.039; 
dichogamy: 23 .5%; average seed set : 2 . 2 1 ;  vector required to achieve pollination, fertilization and seed set; open 
pollinated plants set highly variable amounts of seed under natural conditions; plants in low density patches are pollen 
limited but the size of population does not influence pollination success; 25% of precocious stigmata receive pollen. 
CHR, 1 93141, Northwest Nelson, South-west o/Dun Mountain, Windy Point, on Dun tramline. 25385, 59844, Given DR, 1963; CHR, 212652, Dun Mountain track, half a 
mile b�rore Roding-Maitai Saddle, 253-, 598--, Given DR, 1 960; CHR, 24229, Dun Mountain, Mineral Belt, 2541-, 5984-, Moore LB, 1 939; CHR, 273 147, Wairau 
Valley, Red Hills, 25 1 2-, 5944-, Druce AP, 1 974; CHR, 295240, Dun MOllntain, 2541-, 5984-, Wall A, 1 921; CHR, 295244, Dun Mountain, 2541-, 5984-, Gibbs FG; CHR, 
295245, Dun Mountain, 2541-, 5984-, Gibbs FG, 1904; CHR, 295249, Dun Mountain, 2541-, 5984-, Gibbs FG; CHR, 295251, Dun Mountain, 2541-, 5984-, Gibb FG; 
CHR, 295252, Dun Mountain, 2541-, 5984-, SainsbU/y GOK, 1922; CHR, 29837, Dun Mountain, 2541-, 5984-, MasonR, 1941; CHR, 301561, Dun Mountain, 2541-, 
5984-, Talbot H; CHR, 387382, Bryant Range, Dun Mountain, 2540-, 5984-, Druce AP, 1 98 1 ;  CHR, 387447, Wairau Valley, Red Hills, Upper Motueka River, 2514-, 
5952-, Druce AP, 1980; CHR. 401 655, Motueka Valley, (len branch), Gordon Range, 2512-, 5956-, Druce AP, 1 985; CHR, 405021 ,  Nelson, Dun Mountain, Windy Point, 
25385, 59844, Park GN, 1 975; CHR, 60319, Wairall Mountains, Dun Mountain, 254--, 598-, McKay W; CHR, 97282, Dun Mountain, 254--, 598--, A Jlan HH; Gibbs FG; 
Authors records: Red Hills Ridge, 25132, 59453; Red Hills Ridge, 25146, 59514; Red Hills Ridge, 25145, 59508; Red Hills Ridge, 251 35, 59536; Porters Ridge, 251 23, 
59532; Porters Ridge, 251 1 9, 5951 8; Porters Ridge, 25 132. 59530; Coppermine Saddle, 25399, 59845; Dun Saddle, 25407, 59841; Dun Saddle, 25406, 59843; Dun 
Saddle, 25409, 59843 
1 36 
Endemicity: M ineral belt, E. Nelson, S. Is.  
Reproduction: P; DD 
Typical population size: L 
Threat status: None 
Main and top inset: A WR; Lower inset: BM 
Distribution records 
(accuracy) 
• CHR ( l OO m) 
o CHR ( l km) 
* Authors ( l OO m) 
D CHR (10 km) 
' Mt Arthur 
' Mt Owen 
o �Red Hill 
� 
' St Arnaud 
1 0  km 
1 37 
Myosotis macrantha (Hook. f.) Benth. et Hook. f. 
Ranking: None 
Abundance and Distribution: This species occurs throughout the South Island, mainly to the west of the Divide. 
Populations of this species are typically moderate to large. 
Habitat: Alpine, on or at the edges of rock outcrops, usually on the south facing aspect. 
Threats: None 
Distinguishing features: Plants usually consist of several rosettes, the leaves of which are variable throughout the 
South I sland. The rosette leaves of the Nelson forms are usually glabrous underneath, except for some hairs on the 
midrib. The variably coloured flowers distinguish this species from others. The flowers can be dark-purple-brown, 
bronze or yellow in colour, have yellow scales, are scented and of the funnel blossom type. The inflorescence is 
compact throughout flowering; each plant can have many inflorescences, which, along with synchronous opening of 
flowers, all contribute to producing a large floral display. 
Plants can be distinguished from M. monroi by the green rather than bronze rosette leaves, but more reliably by the 
coloured flowers. Plants are similar vegetatively to those in the lyallii/elderi complex but have larger, more robust leaf 
size and very different flowers. The flowers are most like those of M arnoldii, but plants are very easily distinguished 
from M arnoldii by green rather than silver leaves .  
Reproduction and recruitment: Study sites: Mt.  Mytton and Lake Peel. Results: herkogamy: 2 .8  - 5 .2  mm; seLfing 
rate: 0.042; dichogamy: 25 .6%; average seed set: 2 .9 ;  vector required to achieve pollination, fertilization and seed 
set; open pollinated plants set highly variable amounts of seed under natural conditions; plants in low density patches 
are pollen limited but the size of the population does not influence pollination success. 
CHR, 24228, Mount Arthur, 2483·, 5998·, Moore LB, 1939; CHR, 36067, Iron Hill, 2477·, 601 1·, MasonR, 1 942; CHR, 51505, TasmanMountains, Iron Hill, 2476-, 
601 1 ·, Mason R, 1 942; CHR, 76066, Mount Arthur, 2483·, 5998·, HayJA, 1 950; CHR, 76999, Mount Arthur, 2483·, 5998·, HayJA, 1 952; CHR, 151028, Cobb Valley, 
Iron Hill. 2477·, 601 1·, Moore LB, 1 964; CHR. 1 91 793, Mount Art/mr. basin at head o/Horseshoe Creek, 2484·, 6000-, Ritchie IM. 1 969; CHR, 1 91 797, Mount Arthur, 
basin at head o/Horseshoe Creek, 2484·, 6000-, Ritchie JM, 1969; CHR, 237862, Mount Arthur, 2483·, 5998·, Simpson C, 1 970; CHR, 252254, Northwest Nelson, Cobb 
Valley, Thorns' Creek, 2474-, 6008-, Druce AP, 1 970; CHR, 273650, Northwest Nelson, Mount Patriarch, 2468-, 5975-, Druce AP, 1 974; CHR, 277622, Northwest 
Nelson, Mount Arthur, 2484·, 6000-, Druce AP, 1975; CHR, 279021,  Northwest Nelson, Cobb Valley, 2473-, 601 2-, Druce AP, 1 970; CHR, 295242, Mount Peel, 2475., 
6007·, Wall A, 1921;  CHR, 326763, Mount Peel, 2475·, 6007-, Talbot H, ; CHR, 3551 83, Northwest Nelson, Matiri Range, Head of Larrikin Creek, 2452-, 5960., Druce 
AP, 1 979; CHR, 3585 15, Northwest Nelson, Garibaldi Ridge, 2460-, 5996-, Druce AP, 1980; CHR, 365449, Northwest Nelson, North West of Mount Benson, 2472-, 
6015-, Druce AP, 1980; CHR, 371 665, Northwest Nelson, Cobb Valley, Upper Cobb River, Thorns' Creek, 2475·, 6008·, Ritchie IM. 1970; CHR, 387041 ,  Richmond 
Range, West of Old Man, 2534-, 5965-, Druce AP, 198 1 ;  CHR, 389033, Northwest Nelson, South Arthur Range, Near Luna Lake, 2465-, 5977-, Druce AP, 1982; CHR, 
395640, Northwest Nelson, Bald Knob Ridge, 2462-, 5957-, Courtney S, 1989; CHR, 401 060, Northwest Nelson, Anatoki Range, 2480·, 6028-, Druce AP, 1 984; Authors 
records: Mt Mytton, 24748, 60097; Mt Mytton, 24748, 60097; Lake Peel, 24767, 60069; Horseshoe Basin, 24843, 59993 
1 3 8  
Endemicity: S. Is. 
Reproduction: P; DD 
Typical pOllUlation size: L 
Threat status: None 
All photos: A WR 
o 
o 
o 
Distribution records 
(accuracy) 
• CHR ( l OO m) 
o CHR ( l  km) 
* Autbors ( l OO m) 
o CHR ( l O km) 
o 
� Mt Arthur 
- Dun Mt 
o 
- Mt Owen 
- Red Hill 
- S! Arnaud 
1 0  km 
o 
1 3 9  
Myosotis laeta Cheesem. 
Ranking: M. laeta was listed as Vulnerable in the previous Botanical Society lists (Cameron et al, 1 995) and is now 
classified a s  Range Restricted (de Lange et al, 1 999). 
Abundance and Distribution: M. laeta has a very limited geographic distribution, restricted to the serpentine mineral 
belt east of Nelson. There are two known populations, one on the Red Hills Plateau and the other on the lower flanks of 
Mt. Starveall. The Red Hills Plateau population is large ( 1 0's of thousands of individuals) although it occurs in one 
small area (2x 1km). The extent of the Mt. Starveall population is not known. 
Habitat: Ultramafic, non-forest, tussock-manuka shrubland, 900- 1 2 00m 
Threats: manuka regeneration and recolonisation into the Red Hills P lateau population (Dickinson, pers. comm.).  
Distinguishing features: Plants usually consist of a single rosette, the leaves of which have bronze margins, with short, 
fine hairs, longer at margins and rctrorse underneath. The inflorescence, usually one per plant, elongates over the 
flowering period with flowers opening sequentially. Flowers are unscented, of the funnel blossom type but with long 
filaments and extended anthers. The corolla is white-creanl col oured with yellow scales. 
Plants can be distinguished from M. rnonroi by their very different inflorescence type and flowers, but in the absence of 
flowering material, can be distinguished by the absence of hairs on the underside of the rosette leaves. Plants are 
similar to members of the M. australis aggregation, but can be reliably distinguished with flowering specimens by the 
colour and shape of the corolla, which is tube form with short filaments in the latter. The rosette leaves offer further 
differences, which in M laeta have that bronze margin; the hairs are short, less crowded and appressed. Plants can be 
distinguished from M. macrontha in the absence of flowering specimens by the absence of hairs on the undersides of 
tlle rosette leaves in the latter. 
Reproduction and recruitment: Study site: Red Hills. Results: herkogamy: 0 . 9  - 1 . 8 mm; selfing rate : 0.02; 
dichogamy: 8 . 3%; average seed set: 1 . 8 ;  vector required to achieve pol lination, fertilization and seed set; open 
pollinated plants set highly variable amolmts of seed under natural conditions; plants in low density patches are pollen 
limited. 
CHR, 387376, Richmond Range, Mount Starveall, 2528-, 5971-, Oruce AP, 1 98 1 ;  CHR, 387462, Wairau Valley, Red Hills, 2509-, 5941 -, Druce AP, 1 980; CHR, 489540, 
Wairau, Red Hills, 2509-, 5941-, Cheeseman TF, 1852; Authors records: Red Hills, 251 07, 59432; Red Hills, 25094, 59425; Red Hills, 25095, 594 1 9; Red Hills Plateau, 
25 1 1 4, 59436; Starveall, 25293, 597 15  
1 40 
Endemicity: Mineral Belt, E. Nelson, S. Is. 
Reproduction: P; DD 
Typical population size: L & S 
Threat status: RR. 
. Mt Arthur 
· Mt OWen 
Distribution records 
(accuracy) 
• CHR ( l OO m) 
o CHR ( l  km) 
� Authors ( l OO m) 
CHR ( 1 0  km) 
' Dun  Mt 
' Red Hill 
· S! Arnaud 
10 km 
Left: AMB; Right: A WR 
14 1  
Myosotis brockiei Moore et Simpson 
Ranking: M brockiei has appeared in past lists in Category I, (Molloy and Davis, 1 994), and as Rare, (Cameron et al, 
1 995). It is now considered Range Restricted (de Lange et al, 1 999). 
Abundance and Distribution: M. brockiei has a restricted distribution, which is centered, around the Cobb Valley, 
within which there are several small, often isolated populations. This species is confined to two types of geological 
substrate; an ultramafic belt, the Cobb Igneous Complex, which has a magnesite-talc composition, and on various 
limestone outcrops. 
Habitat: Basicole, limestone and ultrarnafic outcrops, often growing in very little soil, within forest, or at forest 
margins, sea l evel - tree-line. 
Threats: Small population sizes that are typical of this species coupled with restricted geographic distribution; goats 
damaging habitat (Flora Valley limestone remnant populations; Gorge Creek), goat browse (Gorge Creek); Hieracium 
invasion of habitat ( Gridiron Creek).  
Distinguishing features: This species has white, unscented, brush blossom type flowers with very long, narrow 
filaments and a very narrow and short corolla tube (� l x l  nun) with bright yellow scales. Flowers open sequentially, 
and the inflorescence elongates over the flowering period. Plants can have one to several rosettes, the leaves of which 
are quite variable in shape, size and hairs. The Magnesite Quarry plants have a relatively sparse covering of hairs that 
are more or less appressed. These plants can only be distinguished from M. petiolata ss by their leaf shape, as their 
flowers are very similar. M. petiolata ss have a much longer petiole with a shorter, spathulate lamina. The Magnesite 
Quarry plants have a less well defined petiole that tapers gradually from a more elongated, elliptic lamina. More typical 
plants in the species have larger, more robust leaves with crowded leaf hairs that are not appressed which give the 
leaves a velutinous texture. These plants bear much more resemblance to M. concinna in the vegetative form but can be 
distinguished by the appressed hairs on the rosette leaves, and more reliably by the very different flowers, which in M. 
concinna are yellow with a longer corolla tube. 
Reproduction and ."ecruitment: Study sites: Magnesite Quarry, Cobb Gorge, Flora Valley. Results: herkogamy: 
2 . 7  - 4 . 9  mm; selfmg rate: 0.042; dichogamy: 1 0 .8%; average seed set: 1 . 4; vector required to achieve pollination, 
fertilization and seed set; open pol1inated plants set highly variable amounts of seed under natural conditions; plants in 
low density patches are pollen limited but the size of the population does not influence pollination success. 
CHR, 121 708, Richmond, e.t garden. 2483-, 6012-, Brockie WB, 1 968; CHR, 171679, Richmond, garden. 2483-, 6012-, Brockie WB, 1966; CHR, 188084, Richmond, 
garden ofMr W Brockie, 2483-, 6011-, Brockie WB (received), 1968; CHR, 208218, MO/mt Arthur Tableland, Salisbury Open, 2480-, 6002-, Brockie WB, 1 969; CHR, 
227877, Graham Valley, Mount Arthur, 248--, 600-, Brereton J, 1974; CHR, 233860, Northwest Nelson, Cobb Valley, 248--, 601-, Brockie WB, 1 965; CHR, 271212, 
Cobb Valley, 248--, 601-, Talbot H. 1 964; CHR, 277574, Northwest Nelson, Mount Arthur Tableland, near Salisbury Hut, 2480-, 6001 -, Druce AP, 1975; CHR, 3 1 1 71 7, 
Northwest Nelson, Cobb Valley, Magnesite Quarry, 2483-, 6012-, Druce AP, 1977; CHR, 3 1 1 7 1 8, Northwest Nelson, Cobb Valley, Magnesite Quarry, 2483-, 601 2-, 
Druce AP, 1 977; CHR, 3 1 1 722, Northwest Nelson, Takaka Valley, 2483-, 6005-, Druce AP, 1977; CHR, 335754, Mount A rthur Plateau, 248--, 600-, Wall A, 1 930; CHR, 
365422, Northwest Nelson, Northwest of Mount Benson, 2472-, 6015-, Druce AP, 1980; CHR, 365506, Northwest Nelson, Cobb Valley, 2483-, 6012-, Druce AP, 1979; 
CHR, 401375, North ofCobb Darn, Magnesite Quarry, 24834, 60124, Macmillan BH 88/35; Fife Al, 1 988; Authors records: Cobb Ridge, 24834, 601 04; Gridiron Ck, 
24843, 60038; Salisbury Open, 24808, 60020; Dry Rock, 24814, 60033; Flora limestone, 24837, 60050; Asbestos, 24841, 60085; Mt Mytlon, 2475 1 ,  60092; Cobb Gorge, 
24838, 601 22; Cobb Gorge, 24837, 60 124; Cobb Gorge, 24837, 60122; Mg Quarry, 24834, 601 24; Gorge Ck, 24973, 60288; Gorge Ck, 24976, 60290 
1 4 2  
Endemicity: N.W. Nelson, S. Is. 
Reproduction: P; DD 
Typical population size: S 
Threat status: RR 
Main photo: AMB; Left and right insets: BS 
L .  Otuhi 
Distribution records 
(accuracy) 
• CHR ( 1 00 m) 
o CHR ( l  km) 
• Authors ( lOO m) 
o CHR ( l 0 km) 
Gorge Creek � 
o 
o 
Ol> � 
" 
. Mt Arthur 
· Mt Owen 
. Red Hill 
· St Arnaud 
· Dun Mt 
1 0  km 
143 
Myosotis brockiei Moore et Simpson 'otuhie' 
Ranking: None 
Abundance and distribution: Very limited geographic range, only a few plants known hanging from limestone cliffs 
Habitat: Coastal, calcicole, limestone cliffs, growing directly out of limestone crevices, no soil 
Threats: Recruitment failure, habitat modification, grazing by sheep and cows, small number of plants known in a very 
small geographic area 
Distinguishing features: Plants usually consist of many rosettes matted together, usually hanging from  vertical cliffs 
above browse height. Inflorescences elongate throughout flowering and flowers open sequentially. Flowers are white, 
unscented brush blossom types with overlapping, rounded corolla lobes. 
Plants can be distinguished from M. brockiei by their overlapping corolla lobes, corolla tube (�2 mm) is not as narrow 
and very different habit. 
Reproduction and recruitment: Study site: Lake Otuhie. Results: herkogamy: 1 . 5  3 . 4  mm. 
Herkogamy measurements suggest a vector is required to achieve pollination, fertilization and seed set. The population 
density patterns expected from species with this type of pollination syndrome are not seen. Seed set counts from one 
plant were very low, indicating pollination failure. Vegetative reproduction appears to be maintaining this population at 
Lake Otuhie. 
CHR. 497375, Lake Otuhie, 2459., 6058·, Me/calfU; Heenan P 84194, 1993, Authors records: Lake Otuhie. 24596. 60584; Lake Otuhie, 24595, 60587;  Lake Otuhie. 
24594, 60587 
1 44 
Top photos:  AMB; Lower photos:  BS 
Gorge Creek plants 
(left) and Lake 
Otuhie plants 
(below) . Note 
purple edged 
corollas 
1 45 
Myosotis spathulata Forst. F. IM.  tenericaulis Petrie 
Ranking: None 
Abundance and Distribution: Widespread but sparse throughout New Zealand including the Chathams. 
Habitat: basicole, fertile, dry substrates, shady cave entrances, overhangs, forest, sea level - treeline 
Threats: None 
Distinguishing features: Plants are small, generally prostrate and usually consist of a single rosette but, as they can 
form roots from decumbent lateral branches, they can form a mat of rosettes. Leaves are small and spathulate with 
short, sparse, appressed hairs, similar on the underside. The inflorescence is prostrate and elongates over the flowering 
period as the bracteate flowers open sequentially. There will be a maximum of three flowers out at any one time on 
each inflorescence. Flowers are small, white, tube-blossom type with yellow scales. Corolla lobes vary from flat to 
spreading as anther exertion increases. 
Plants can be distinguished from M. pygmaea by their erect vegetative habit, their rosette leaves which are spathulate 
with a well defined petiole and appressed hairs on both sides of the leaves. Plants are very similar vegetatively to M. 
petiolata ss. and can only reliably be distinguished by their very different flowers. 
Reproduction and recruitment: Study site: Flora Valley; Results: herkogamy: 0 mm; selfing rate: 0 .92; 
dichogamy: 9 .8°1<); average seed set: 3 .7 ;  vector not required to achieve pollination, fertilization and seed set; open 
pollinated plants set unvarying high levels of seed under natural conditions; plants in low density patches are never 
pollen limited. The consistently high levels of seed set under natural conditions suggests population growth is probably 
not seed limited. 
CHR, 1291 15, Brighlwater, Snowdency Bush 2518-, 5981-, Talbot 11, 1962; C11R, 225961, Snowdon's Bush, 2518-, 5981-. Simpson MJA 6957, 1972; CHR, 269155, 
t1mmn<lar,?Y. Snowdons Bush, 2518-, 5981-, Talbot H, 1972; CHR, 269156, Brightwater, Snowdon, Bush, 251 8-, 5981-, Talbot H; CHR, 3 1 1719, Northwest Nelson, 
Valley, 2483-, 6006-, Druce AP,  1977; CHR, 31  1 720, Northwest Nelson, Takaka Valley, 2483-, 6005-, Druce AP, 1 977; CHR, 3 1 1 941,  Northwest Nelson, 
Pikikiruna Ranges, Canaan, 2500-, 6027-, Druce AP, 1 976; CHR, 20821 9, Roding river, 253--, 598--, Brockie WE, 29, 1969; CHR, 208220, CobbRiver Basin, Lake 
Sylvester, 24 78-, 601 1-, Brockie WE, 1 969; C1IR, 269157, Cobb river, between Rocket! and Peel ranges, 247--, 601-, Brockie WE, 1 969; CHR, 269158, Cobb Valley, 
between Rocketl and Peel range,,; 247--, 601--, Brockie WE, 1969; CJJR, 269159, Cobb between Rocket! and Peel ranges, 24 7--, 601-, Kel(v GC, 1 971; CHR, 
2691 60, Between Richmond and Brightwater, Aniseed Valley, 25246, 59797, Elder NL 1 943; CHR, 396052, Northwest Nelson, Cobb Valley, 2470-, 60 1 5- ,  Druce 
Al'. 1 983; CHR, 401639, Motueka river (Jell branch), Gardon range, 2 5 1 0-, 5956-, Druce AP, 1985;  Authors records: Mg Q Rd, 24835, 601 1 8; Old U Tak. Track, 
24844, 60066; Old U. Tak Track, 24849, 60067; Paynes ForcL 24941, 6035 1 ;  Flora limestone, 24837, 60049; ridge to Hoary Head, 24927, 60102; Takaka Hill, 24983, 
60 1 93; StarvealL 25292, 59714 
146 
Endemicity: N.Z. 
Reproduction: S 
Typical population size: S 
Threat status: None 
All photos :  BS  
o 
o 
.. 
.. 
o lI' 
' Mt Arthur 
' Mt Owen 
o 
o 
Distribution records 
(accuracy) 
• CHR ( 1 00 m) 
o CHR ( 1  km) 
* Authors ( 1 00 m) 
D CHR ( l O  km) 
.. 
, Red Hill 
' St Arnaud 0 o 
1 0  km 
147 
Myosotis forsteri Lehm. 
Ranking: None 
Abundance and Distribution: M forsteri has a wi despread distribution, and is found from 38 0 South. Population 
sizes are typically small and it is never common where it occurs. 
Habitat: forest, streamsides, damp seepages, track edges 
Threats: None 
Distinguishing features: These plants usually consist of a single rosette, the rosette leaves of which are spathulate 
often with red gland dots on underside. The hairs are short, stiff, sparse, can be appressed, and are not retrorse 
underneath. The usually single inflorescence elongates during the flowering period as the flowers open sequentially. 
There will be a maximum of three flowers out at any one time on each inflorescence. The tube type flowers are white, 
have yellow scales and are usually small but can vary from 2 . 5  - 7 rrun across. The anthers are always held on 
filaments that vary in length, but keep the antJlers within range of tJle stigma such tJlat self-pollination can occur. 
This species can only be distinguished from M venosa when flowering, by the long filaments, which carry anthers away 
from the stigma, preventing selfing from occurring in tJle latter. This species can have quite similar flowers to M. 
tenericaulis/spathu/ata but is distinguished by its overall size, being a much larger specimen with spreading leaf hairs 
on the rosette leaves, that are not usually appressed and by their ebracteate, erect inflorescence. Plants can be 
distinguished from members of the austra/is complex by ilieir fine, crowded, spreading leaf hairs that are retrorse 
underneath in tJle latter. 
Reproduction and recruitment: Main study site: Myttons Creek. Results:  herkogamy: 0 mm; selfing rate 0 . 975; 
dichogamy: 1 2 . 7%; average seed set: 3 . 9 ;  vector not required to achieve pollination, fertilization and seed set; open 
poll inated plants set unvarying high levels of seed under natural conditions; plants in low density patches are never 
pollen linlited and tJle size of the population does not influence pollination success. 
CHR, 132052, Lake Cobb, 2569-, 6016-, Scotl VM, 1 963; CHR, 140690, Mount Arthur Range, trackfrom Flora Saddle to Mount Arthur, 248--, 600--, Macmillan BH, 
1 963; CHR, 191 798, Upper Takaka River, between Dew Drop Inn and Flora Hut, 248-, 600-, Ritchie IM, 1 969; CHR, 1 91 799, Upper Takaka River, between Broken 
Bridge and Dew Drop Inn, 248--, 600--, Ritchie lM, 1 969; CHR, 235573, Matiri scenic reserve (Owen River), 2464-, 5946-, Kelly 0; Kelly GC, 1 973; CHR, 24227, Flora 
Saddle, 2488-, 6001-, Moore LB, 1 939; CHR, 277555, Northwest Nelson, Tableland, Mount Arthur, Rock Shelter, 248 1 -, 6003-, Druce AP, 1 975; CHR, 277593, 
Northwest Nelson, Mount Arthur Tableland, Cundy Creek, 2478-, 6002-, Druce AP, 1975; CHR, 277742, Flora Stream, north of Mount Arthur, 2485-, 6003-, Druce AP, 
1 975; CHR, 278287, Big River, Gouland Downs, 245-, 603--, SimpsonMJA, 1 973; CHR, 3 1 0592, Northwest Nelson, Above Lake Aorere, 2453-, 6 0 1 6-, Druce AP, 1 977; 
CHR, 355 1 76, Northwest Nelson, Matiri Range, head of Larrikin Creek, 2452-, 5960-, Omce AP, 1 979; CHR, 3585 1 1, Northwest Nelson, Garibaldi Ridge, 2462-, 5997-, 
Druce AP, 1 980; CHR, 365738, Richmond Range, Peak West of Mount Richmond, 254 1 -, 5970-, Druce AP, 1 980; CHR, 401 005, Northwest Nelson, Anatoki Range, 
2478-, 6027-, Druce AP, 1 984; CHR, 4 1 5341 , Nelson, Matakitaki Valley, Peak Creek Track., 24706, 59090, Burke WO 22, 1 984; CHR, 468 1 39, Nelson, Anatoki River, 
2476-, 6027-, Mason R 1 3295, 1977; CHR, 476 1 1 8, Northwest Nelson, Gouland Downs, 2454-, 6035-, Druce AP APD 1 854, 1 992; Authors records Myttons Ck, 24752, 
60 1 08; Aitkens Crossing, 24833, 60049; Cundy Ck, 24785, 60025; L. Peel track, 24785, 60074; Lake Cobb, 24690, 601 67; Lake Cobb, 24694, 601 67; Lake Co bb, 24692, 
60 1 67; Thorn's Ck, 24765, 60090; Hannah Ck, 24737, 60122; Myttons Ck, 24752, 601 08; Mt Arthur track, 24880, 60007; Gouland Downs, 24554, 60350; Gouland 
Downs, 24553, 60349; Gouland Downs, 24554, 60349; Nuggety Ck, 24706, 59676; Kiwi Saddle, 24678, 59774; Peat Creek, 24823, 60068 
1 48 
Endemicitv: N.Z. 
Endemicity: N .Z. 
Reproduction: S 
Typical population size: S 
Threat status: None 
o 
o 
Main and top right insert: A WR; Lower right insert: BM 
o 
o 
co 
o 
' Mt OWen 
o 
o 
o 
Distribution records 
(accuracy) 
• CHR ( 1 00 m) 
o CHR ( 1  km) 
@ Authors ( 1 00 m) I 
o CHR ( 1 0  km) 
' Red Hi l l  
' SI Arnaud 0 
o 
' Dun Mt 
o 
10 km 
1 49 
Myosotis venosa Col. 
Ranking: None 
Abundance and Distribution: M. venosa has a central New Zealand distribution that extends from the central North 
Island to the Nelson region. 
Habitat: Damp, mossy, stream sides, damp cave entrances, track sides, occurs within a range offertilities 
Threats: None 
Distinguishing features: These plants usually consist of a single rosette, the rosette leaves of which are spathulate 
often with red gland dots on underside. The hairs are short, stiff, sparse, can be appressed, and are not retrorse 
underneath. The flowers are white-cream with yellow scales and are unscented. Flowers are of the funnel blossom type 
but with anthers on long filanlents. 
Plants can only be distinguished from M. forsteri by filament length, which is long enough in M. venosa to prevent the 
anthers from contacting the stigma, thus preventing self-pollination from occurring. Plants are similar to M. petioiala 
but can be distinguished by the petiole, which in M petioiata is more defined and longer in proportion to the lamina and 
the leaf hairs are appressed. They have quite different flowers, which are funnel-form with cream coloured spreading 
corolla lobes in M. venosa, as opposed to the brush blossom type with white, flat corolla lobes in M. petiolata. Flowers 
and inflorescences are similar to M laeta but cm be distinguished by the rosette leaves,  which in M. laeta have a bronze 
margin and retrorse hairs underneath. 
Reproduction and recruitment: Study site: Peat Creek; Results: herkogamy: 0 . 5  - 0 . 9  mm; selfing rate: 0.04; 
average seed/set: 1 . 4 ;  vector required to achieve pollination, fertilization and seed set. 
The herkogamy measurements, selfing rate and seed set by open pollinated plants suggest local density will have an 
effect on seed set due to pollen limitation. 
CHR. 140919. Northwest Nelson. Gouland Downs, 2455-, 6035-, Talbot H; Brockie WB, 1 962; CHR. 1 5 1030, CoM Valley, damp slope ofSylvester Stream, 2480-, 6009-, 
Moore LB, 1 9M; CHR, J 8 9 1 60,  Abet Ta;;man National Park, Moa Park, 2504-, 6029-, Druce AP, 1 969; CHR 1 90975, Northwest Nelson, Gouland Downs, 2454-, 6035-, 
Druce AP, 1 969; CHR. 21 9277, North branch o{Wangapeka river, Stone creek, 2463-, 5976-, Macmillan BH 71163, 1 971 ; eHR, 2521 36, Northwest Nelson, Burgoo 
stream, 2469-, 60 1 8 -, Druce AP, 1 970; CHR. 259065, Northwest Nelson, Gouland Downs, 2455-, 6035-, Talbot  H, 1 962; CHR, 259066, NorfhwestNelson, Gouland 
Downs, 2455-, 6035-, Talbot H, 1 962; CHR, 2691 64, Arthur Range, Mount Arthur, south a/Gordons Pyramid, 2483-, 6000-, Talbot H, 1 964; CHR, 2 73653, Northwest 
Nelson, north o/Mount Patriarch near Kiwi saddle, 2468-, 5977-, Druce AP, 1 974; CHR, 278246, Northwest Nelson, Gouland Downs, 2455-, 6035-, 7240, 
1 9 73; CHR, 2 7831 6, Talylor Valley, near Kiwi saddle, 2467-, 5978-, Simpson hilA 7380, 1 974; CHR. 28839, Six mile creek, near Mount Lodestone, 248-, Mason 
R, 1 941; CHR. 387065, near Old Man hut, 2532-, 5964-, Druce AP, 1981; CHR, 87639, Northwest Nelson, Gou/and Downs, 2455-, 6035-, Talbot H, 
1 956; CHR, 87640, Northwest Nelson, 2455-, 6035-, Talbot H, 1 956; Authors records: Peat Creek, 24820, 6007 1 .  
150 
Endemicity: Central N. Is.,  N.W. S. Is. 
Reproduction: P 
Typical population size: S 
Threat status :  None 
All photos :  BS 
o 
Distribution records 
(accuracy) 
• CHR ( lOO m) 
o CHR ( 1  km) 
• Authors ( l OO m) 
D CHR ( 1 0  km) 
o 
" 
?Mt Arthur 
· Mt Owen 
. Red Hi l l  
· St Arnaud 
· Du n  Mt 
o 
1 0  km 
1 5 1  
Myosotis petiolata Hook. f. var. petiolata 
Ranking: This species has been considered threatened since 1 994 (Category I in Molloy and Davis, 1994; 
Insufficiently known in Cameron et aI, 1 995) It is  still categorized as Insufficiently Known in the latest list (de Lange 
et aI, 1 999). This is the rarest species of Myosotis known in the area, but requires survey to detennine the true limits of 
its distribution. 
Abundance and Distribution: The historical distribution of this species is a disjunct one, with a few collections 
having been made in the East Coast and in N. W. Nelson. Currently, this species is only known from two populations 
near Asbestos Cottage, in the Upper Takaka Valley, one of which contains just three plants, the other a few hundred 
plants in a tiny area ( l OOxlOm). This is very rare and the Nelson populations may be the only extaut populations in 
existence. 
Habitat: The two known sites are quite different; one is under an ultramafic rock overhang, and the other is in a damp, 
tussock-shrub, seepage. 
Threats: Small total number of known plants, from two small populations, that occur in a very restricted are� pollen 
limitation, lack of recruitment; chance event such as a landslide could eliminate most of the known plants in existence. 
Distinl.,'llishing features: These plants usually consist of a single rosette, the leaves of which consist of a small, more 
or less orbicular lamina Witll very long petioles, > 4 x as long as the lamina. There is usually one inflorescence per 
plant, sometimes branched, tllat elongates during flowering and flowers open sequentially. Flowers have white, 
un scented brush-blossom type flowers, with a narrow, short corolla tube with bright yellow scales and flat lobes. 
Flowers and inflorescence type can not be distinguished from 10. brockiei. These two can only be distinguished by the 
orbicular leaf blade and long narrow well defined petioles on M. petio/ata. Vegetatively plants can not be distinguished 
from M. ,\pathulata / tenericaulis plants, but they have very different flowers and flowering specimens are required for 
reliable identification. 
Reproduction and recruitment: Study site: Asbestos population. Results: herkogamy: 2 - 5 . 1  nun; selfing rate: 
0 .0275; average seed set: 2 .6; vector required to achieve pollination, fertilization and seed set; hand polliuations 
revealed plants were pollen limited. 
The reasonable level of seed set by these plants under natural conditions suggests plants are getting adequately 
pollinated, at least in the flowering season when the study was conducted. 
CHR, 1 91 795. Upper Takaka River. near Broken Bridge. 2483-, 6006-. Ritchie IM, 1 969; CHR, 401 092. Northwest Nelsol\ Takaka Valley. 2484-. 6008-. Druce AP. 1 989;  
CHR. 8781 1. Upper Takaka River. Peat Creek. 248--, 600--. JIayJA. 1 950; Authors records: Asbestos. 24840. 60086; Asbestos. 24844. 60077 
1 5 2  
Endemicity: E. Coast, N. Is & N.W. 
Nelson, S. Is. 
Reproduction: P 
Typical population size: S 
Threat status: I 
All photos: A WR 
. Mt Arthur 
' Mt Owen 
Distribution records 
(accuracy) 
• CHR ( lOO m) 
o CHR ( J  km) 
@ Authors Cl 00 m) 
D CHR ( l 0  km) 
' D u n  Mt 
. Red Hi l l  
· St Amaud 
10 km 
1 53 
Myosotis arnoldii L.B. Moore 
Ranking: M arnoldii appeared on the Botanical Society Local Plant list (Cameron et al, 1 995) and is currently listed 
as Range Restricted (de Lange et aI, 1 999). 
Abundance and Distribution: M arnoldii has a disjunct distribution. It occurs on a couple of peaks in the Arthur 
Range (Crusader and Hoary Head), and over on the Chalk Range, in the Kaikouras. It has very restricted geographic 
distributions, but is reasonably plentiful where it occurs and populations are typically large. 
Habitat: Alpine, calcicole, marble and limestone mountains 
Tbreats: None 
Distinguishing features: The unique combination of dark purplish-black, scented, funnel blossom flowers with yellow 
scales and silver leaves along with its highly restricted distribution make identification of this species mistake free. 
Plants usually consist of several rosettes, the leaves of which are distinctively silver. This species has a compact 
inflorescence that does not elongate in fruit, there can be many inflorescences per plant, which along with flowers 
opening synchronously, results in a large floral display. There is a difference between plants of Marlborough and 
Nelson populations, Marlborough plants have hooked hairs on their calyces, but the Nelson plants do not. 
In the absence of flowering specimens, these plants Gm be distinguished from M. angustata by their distinctive silver 
leaves. 
Reproduction and recruitment: Study site: Hoary Head. Results: herkogamy: 2 .2  7 . 1  mm; dichogamy: 20%. 
Herkogamy measurements suggest a vector is required to achieve pollination, fertilization and seed set. 
CHR. J 32039, 34 QuebecRuad, 2493-, 6008-, Given D, 31, 1 962: CHR, 208212, Mount Hoaryhead, 2493-, 6008-, BreretonJ, 1 971 : CHR, 243884, Lincoln, Botany 
Division, 2493-, 6008-, Moore LB, 1 974; CHR, 258649, Northwest Nelson, Arthur Range, Hoary Head, 2493-, 6008-, Sneddon RV, 1973; CHR, 258969, Mount Hoary 
Head, 2493-, 6008-, Sneddon BV, 1 973; CHR, 258970, cultivated, 2493-, 6008-, Moore LB, 1973; CHR, 2691 36, Northwest Nelson, Hoary Head, 
2493-, 6008-, Brereton J, 1970; CHR, 387709, Northwest Mount Hoery Head, 2493-, 6008-, Druce iI.P, 1 980; Authors records: Hoary Head, 24936. 60080; 
Hoary Head, 24935, 60087: Hoary Head, 24937, 60086: Hoary Head, 24935, 60084; Hoary Head, 24936, 60085; Crusader, 24925, 60067. 
154  
Endemicity: N . W. Nelson & E. Marlb.,  S. 
Is .  
Reproduction: P 
Typical population size: L 
Threat status: RR. 
Main and top right AMB; Lower left: BM 
Distribution records 
(accuracy) 
• CHR ( 1 00 m) 
o CHR ( l  km) 
• Authors (lOO m) 
D CHR ( 1 0  km) 
. Mt Arthur 
' Dun Mt 
- Mt OWen 
- Red Hil l  
- St Arnaud 
10 km 
1 55 
Myosotis angustata Cheesem. 
Ranking: M. angustata appeared on the Botanical Society Local Plant list (Cameron et aI, 1 995) and is currently listed 
as Range Restricted (de Lange et aI, 1 999). 
Abundance and Distribution: This species is known to occur over a small geographic rdllge in typically small 
populations. 
Habitat: Alpine, calcicole, marble mountains, steep but stable scree slopes 
Threats: small geographic range, small populations, possible over collecting at the Mount Arthur population due to 
ease of access. 
Distinguishing features: These plants usually consist of several rosettes, the leaves of which are narrow and bluish 
green in colour with leaf hairs that are both short and long, appressed, not retorse underneath. The inflorescence 
remains compact throughout flowering, which along with synchronous opening of flowers gives it an almost capitate 
appearance. Each plant can have several inflorescences which along with the capitate cymes produce a large floral 
display. Flowers are white, un scented, tube-blossom type with yellow scales, short filaments and variable style length. 
Plants c,m be distinguished from M. tavers-ii, which has similar inflorescence type and flowers, by their leaf hairs which 
in M. traversii are long, overlapping, not appressed, and retrorse underneath. An additional difference is that M 
traversii has hooked hairs on its calyces. Plants can be distinguished from .M. macrantha by their very different 
flowers, but in absence of flowers, in M. macrantha usually leaf hairs are absent on the under sides of the rosette leaves. 
Reproduction and recruitment: Study site: Mount Arthur. Results: herkogarny: 0 1 . 5  mm. 
The herkoganlY measurements suggest this species has both selfing and non-selfing type flowers on different plants 
within the population. This was due to variation in the length of the style, carrying the stigma either above or at the 
level of the ,mthers. The herkogamy measured suggests some of the plants in the population will not be affected by 
density in their reproductive effort. 
CHR, 187715. Northwest Nelson. Top o,fMount Arthur. 241'3-. 5998-. RUchie MA; Ritchie IM, 1 970; CHR, 1 87735 .  Northwest Nelson. Top of Mount Arthur, 2483-, 5998-, 
Ritchie IM, 1 970; CHR, 1 91 794. Northwest Nelson, Mount Arthur, basin at head o/Horseshoe Creek, 2484-. 6000-, Ritchie IM, 1 969; CHR, 20821 7, Northwest Nelson, 
Mount Hoaryhead, 2493-, 6008-, Brereton JA, 1971 ; CHR, 277613 ,  Northwest Nelson. Mount Arthur, 2483-, 5998-, Oruce AP, 1 975; CHR, 295297, Northwest Nelson, 
Mount A rthur. 2483-, 5998-, Wall A, 1 921 ; CHR, 387628, Northwest Nelson, Mount Arthur, 2483-. 5998·, Oruce AP, 1 982; CHR, 387640, Northwest Nelson, Iron Hill,  
2476-, 601 2-, Oruce ",P, 1 982; CHR. 393696, Northwest Nelson, Owen Culliford Hill, 247 1 ·, 5966-, Oruce AP, 1 983; CHR, 97309, Moun/ Ar/hur. 2483-, 5998-, 
GiMs FG, 1 895; CHR, 97310, NorthwestNels-on, Cobb Valley; 24774, 60144. Gibbs FG; Authors records: MtArthur. 24836, 59986; Mt Arthu[, 24833. 
59986; Mt Arthur. 24834. 59985; Mt Bell, 24732, 59633 
1 56 
Endemicity: N . W. Nelson 
Reproduction: P&S 
Typical population size: S 
Threat status :  RR. 
o 
0'Mt Arthur 
o 
·'Mt Owen 
Distribution records 
(accuracy) 
• CHR ( l OO m) 
o CHR ( l  km) 
• Authors ( 1 00 m) 
D CHR ( I O km) 
. Dun Mt 
. R e d  Hill 
· St Amaud 
10 km 
All photos: B S  
1 5 7  
Myosotis concinna Cheesem. 
Ranking: M concinna appeared on the Botanical Society Local Plant list (Cameron et al, 1 9 9 5 )  and is currently li sted 
as Range Restricted (de Lange et aI, 1 999). 
Abundance and Distribution: M concinna is endemic to the Mount Owen marble massif. It has a very restricted 
geographic distribution but is quite common where it occurs. Population sizes are typically large. 
Habitat: Calcicole, south facing marble bluffs and rock ledges, or close to rock ledges, stable marble screes, from 
about 1 3 00 - 1 870 m a.s.1 .  
Threats: none 
Distinguishing features: Plants usually consist of several rosettes, the leaves of which have a crowded covering of 
hairs that are fine, silky and appressed. The inflorescence elongates during flowering witll flowers opening 
sequentially. The flowers are yellow in colour, scented, and of the brush blossom type with very long fi laments. 
Plants are difficult to distinguish from M brockiei using leaf characters alone as both have fine overlapping hairs on 
their rosette leaves, but in M. concinna they are silky and appressed, in M. brockiei they are arctuate. Although their 
habitats overlap, M. concinna is the only one found in the high alpi.ne zone, and never below tree line. They can 
reliably be disti nguished by tlleir flowers, which in M. concinna are yellow with long corolla tube, in M. brockiei 
flowers are whjte with a very short tube. M. concinna can be distinguished from M. macrantha in the absence of 
flowers by leaf hairs, which are usually absent on the undersides of the rosette leaves in M. macranlha. Plants can be 
distinguished fro m M. angustala by their rosette leaves which, in M. anguslata, are very narrow, with short and long 
leaf hairs, tllat are 110t retrorse undemeath. Plants can be distinguished from M a . . ' small white' apart from the general 
size of the plant, M. concinna being a much larger plant, by rosette leaf hairs which in M. concinna are appressed, in 
' small white' are not. 
Reproduction and recruitment: Study site: Granity Pass. Results : herkogamy: 3 . 6  - 6 . 2  mm. 
The herkogamy measurements suggest this species requires a vector to achieve pollination, fertilization and seed set. 
CHR, 225936, Mount Owen, 247--, 596--, MossJB, 1 971; CHR, 227638, Mount Owen, 2471-, 5961-, SimpsonMlA 6673, 1972; CHR, 227638, Mount Owen, 2471-, 5961-
, Bultin M. 1972; CHR, 227660, Mount Owen, Granity Pass, 2473-, 5964-, Simpson M1A 6695, 1 972; CHR, 227661, Mount Owen, Granity Pass, 2473-, 5964-, Simpson 
M1A 6696, 1972; CHR, 233848, Mount Owen, 2471-, 5961-, Wellington Botanical Society, 1 972; CHR, 249718, Owen Range, Granity Pass, 2473-, 5963-, Druce AP, 
1972; CHR, 335755, Mount Owen, 2471-, 5961-, Townson W; CHR, 335756, Mount Owen, 2471-, 5961-, Cheeseman TF, 1883;AK, 7549, Mount Owen, 247--, 596-, 
Cheeseman TF; Authors records: Granity Pass, 24744, 59646; Granity Pass, 24741 , 59645; Granity Pass, 24737, 59646; Granity Pass, 24738, 59645; Billies Knob, 
24739, 59650; Billies Knob, 24741 ,  59655; Mt Bell, 24735, 59638; Castle Basin, 24710, 59609; Castle Basin, 24706, 59604; Culliford Ridge, 24722, 59676. 
1 5 8 
Endemicity: N . W. Nelson, S. Is. 
Reproduction : P 
TypicaJ population size: L 
Threat status :  None 
All photos: BS 
. Mt Arthur 
''is­
' Mt Owen 
. Red Hill 
· St Arnaud 
CHR ( 1 0  km) 
' Dun Mt 
1 0 km 
1 59 
Myosotis lyaILii Hook. F. / M elderi L.B. Moore 
Ranking: None 
Abundance and Distribution : lower North Island and South Island. Known to occur in small populations. 
Habitat: sub-alpine - alpine, rocky sites 
Threats: None 
Distinguishing features: TIllS species complex has little separating individuals other than filament length. Plants 
usually consist of several rosettes, tlle leaves of which have an obovate lanlina which is longer tllan the winged petiole, 
with long hairs which are absent undemeath. The inflorescence is compact throughout flowering and each plant can 
have many inflorescences, although flowers open sequentially. Flowers are white, unscented, tube blossom type, with 
yellow scales. Only the first few flowers on tlle cyme are bracteate, and style and filament length vary. 
TIllS complex has small floral character differences in style length and filanlent length. Other tllan that all vegetative 
characteristics are very similar. 
Plants can be distinguished from M. pygmaea S.1. in being a larger plant with multiple rosettes. Rosette leaf shape is 
different with a lamina longer tllan the winged petiole, whereas in M pygmaea they are more equal in length. Calyx 
properties differ; in M Iyallii / elderi, the calyx is lobed to V2 way, ,with soft, spreading hairs whereas in M. pygmaea 
the calyx is lobed to less than V2 way, and some of the short hairs on the calyx are retrorse. There is a major difference 
in the flowers which are twice the size inM  lyallii / elderi, both in corolla width and length. 
Plants can be distinguished from M traversii by having sequentially opening flowers, larger, flatter corolla lobes and no 
hairs on the undersides of the rosette leaves. Plants can be distinguished from M. macrantha, which is very similar 
vegetatively, by their smaller, less robust leaves but more reliably by their very different flowers which are only white 
in M Iyallii / elderi. 
Reproduction and recruitment : Study sites: Kakapo Peak and Mt. Gibbs. Results: herkogamy: 0 - 1 . 4 mm. 
The herkogamy measurements suggest iliis species has both selfmg and non-selfing type flowers on different plants 
wiiliin the populations. TillS was due to variation in the length of the style, carrying the stigma eiilier above or at tlle 
level of the anthers. Variation in filanlent length and anther exertion was also observed. The herkogamy measured 
suggests some of tlle plants in the population will  not be affected by density in ilieir reproductive effort . 
CHR, 395797, Northwest Nelson, Glasgow Range, 243 1 ·, 5955., Druce AP, 1986; CHR, 395804, Northwest Nelson, Glasgow Range, 2431 ·, 5955·, Druce AP, 1 986; 
CHR, 35909 1 ,  Buller, Glasgow Range, 243 19, 59544, Loh G; CHR, 3871 39, Northwest Nelson, Scarlet Range, Mount Brilliant, 245 1 ·, 598 1 ., Druce AP, 1 98 1 ;  CHR, 
3 1 1 607, Northwest Nelson, above Lake Aorere, 2453·, 601 6·, Druce AP, 1 977; CHR, 3 1 0505, Northwest Nelson, Mount Centre, 2454-, 6015·, Druce AP, 1 977; CHR, 
3871 35, Northwest Nelson, Herbert Range, Mount Herbert, 2456·, 598 1 ·, Druce AP, 1 98 1 ;  CHR, 3871 36, Northwest Nelson, Herbert Range, Mount Herbert, 2456·, 598 1 ·, 
Druce AP, 1 98 1 ;  CHR, 3871 37, Northwest Nelson, Herbert Range, Mount Herbert, 2456·, 598 1 ·, Druce AP, 1 98 1 ;  CHR, 389955, Northwest Nelson, Mount Kendall, 
2459·, 5982·, Druce AP, 1 983; CHR, 40 I 045, Northwest Nelson, above Lonely Lake, Douglas Range, 2472·, 6025·, Druce AP, 1 984; CHR, 183516, Northwest Ne/son, 
SlImmit of Lead Hill, BOII/der Lake area, 24720, 60348, Rilchie IM, 1 968; CHR, 222760, Northwest Nelson, Mount Goul, 2456·, 6029·, Druce AP, 1973; CHR, 3581 92, 
Northwest Nelson, Cobb Valley, Mount Cobb, 2468·, 6015·, Robins I, 1970; CHR, 363561 ,  Northwest Nelson, Kakapo Peak, 2472·, 6020·, Druce AP, 1980; CHR, 
365452, Northwest Nelson, South East of Island Lake, 2467·, 601 7., Druce AP, 1 980; CHR, 370002, Northwest Nelson, Peel Range, Mount Ranolf, 2469., 60 12·, Druce 
AP, 1 982; CHR, 370034, Northwest Nelson, Peel Range, Mount Prospect, 2469·, 6013·, Druce AP, 1 982; CHR, 389957, Northwest Nelson, Mount Kendall, 2459·, 5982·, 
Druce AP, 1 983; Authors records: Kakapo Peak, 24726, 60206; Mt Gibbs, 24678, 60 1 74. 
1 60 
Endemicity: Lower N. Is., S. Is. 
Reproduction: S & p 
Typical population size: S 
Threat status: None 
All photos: BS 
o 
• 
• 
o 
· Mt Arthu r  
· Mt Owen 
' Red H i l l  
' S! Arnaud 
Distribution records 
(accuracy) 
• CHR ( 1 00 m) 
o CHR ( I  km) 
� Authors ( lOO m) 
CHR ( 1 0  km) 
' Du n  Mt 
1 0 km 
1 6 1  
Myosotis traversii Hook. f. var. traversii 
Ranking: None 
Abundance and Distribution: Northern South Island 
Habitat: Alpine screes 
Threats: None 
Distinguishing features: Plants usually consist of several rosettes, the leaves of which have lots of long spreading 
hairs that are shorter and retrorse underneath. The inflorescence remains compact throughout flowering, which along 
with synchronous opening of flowers gives it an almost capitate appearance. Each plant can have several inflorescences 
which along with the capitate cymes produce a large floral display. Flowers are white, unscented, tube blossom type 
with yellow scales and anthers extending out of the tube on short filaments. 
Plants can be distinguished from M angustata, which has similar flowers and inflorescence, by their wider leaves, l eaf 
hairs which are not appressed, are retrorse underneath, ,md by having hooked hairs on their calyces. Plants can be 
distinguished from lyallii / elderi by the presence of hairs on the undersides of the rosette leaves, smaller ( 1 . 5  mm) 
corolla lobes that are rounded, and more or less capitate inflorescence. Plants can be distinguished from /1/1. macrantha 
by their rosette leaves which have hairs underneath and by their very different flowers which are always white. 
Reproduction and recruitment: Study site: Kakapo Peak. Results :  herkogamy: 0 - 1 . 2  mm. 
The herkogamy measurements suggest this species has both selfing and non-selfing type flowers on different plants 
within the population. This was due to variation in the length of the style, carrying the stigma either above or at the 
level of the anthers. The herkogamy measured snggests some of the plants in the population will not be affected by 
density in their reproductive effort. 
CHR. 2521 08, Northwest Nelson, Peak, 2472-, 6020-, Druce AP, 1 970; CHR, 34872, KakapoPeak, 2472-, 6020-, BufcherJW, 1 946; eHR, 3549 1 6, Northwest 
Nelson, Matiri Range, The Needle, 5 96 1 -, Druce AP, 1 979; CHR, 358439, Northwesf Nelson, Garibaldi Ridge, 2460-, 5996., Druce AP, 1980; eHR. 365454, 
Northwest Nelson, Peak 2472-, 6020-, Druce AP, 1 980; eHR, 387848, Northwest Nelson, Snowden Range, Kakapo Peak 2472-, 6019-, Druce AP, 1 9 8 1 ', CHR. 
40 1 807, South-west South-south-west of Mount Baldy, 2461-, 5906-, Druce AP, 1 984; Authors records: Kakapo Peak, 24728, 60206; Kakapo Peak, 24725, 
60205; Kakapo Peak, 24726, 60205 
162 
Endemicity: Northern S. Is. 
Reproduction: S & p 
TypicaJ population size: M 
Threat status: None 
o 
o 
Distribution records 
(accuracy) 
• CHR (lOO m) 
o CHR (I  km) 
� Authors ( 1 00 m) 
o CHR (lO km) 
. Mt Arthu r  
- D u n  Mt 
- Mt Owen 
- Red Hill 
' St Arnaud 
1 0 km 
1 6 3  
Myosotis pygmaea Col. var. pygmaea and M. p. var. drucei L.B. Moore 
Ranking: None 
Abundance and Distribution: Widespread but sparse throughout New Zealand 
Habitat: Non-forest, coastal salt turf - alpine 
Threats: None 
Distinguishing features: Plants in this complex usually consist of single rosettes that are typically small. 
I nflorescences are prostrate and remain compact throughout flowering. There are not usually more that 3 flowers open 
at any one time on an inflorescence, and fl owers open sequentially. Flowers are small, of the tube blossom type with 
yellow scales and are bracteate. 
Although these two taxa are distinctive in the Nelson region by the traits that di stinguish them in Allan ( 1 96 1 ), they are 
not as easily split when encountered outside the Nelson region. For mapping purposes, the distributions are therefore 
lumped as they can not reliably be separated. 
M. p. var. pygmaea M p. var. c/mcei 
White corolla, acute lobes, corolla 1 . 5-3mm wide Cream -white corolla, obtuse lobes, corolla 3mm wide 
Tips of nutlets visible above caJyx lips in fruit Nutlets completely hidden inside calyx 
Stiff leaf hairs Soft leaf hairs 
Plants can be distinguished from M. spathulata / tenericaulis by their more prostate vegetative habit, and rosette leaves, 
which do not have a well defined petiole and are usually hairless underneath . Plants can be distinguished from M 
lyallii / elderi by their more prostrate habit and inflorescence, smaller overall size and single rosette. Their prostrate 
features distil1guish plants from other small white flowered taxa such as M a. 'small white' and M forsteri. 
Reproduction and recruitment: Study site: Kakapo Peak and Mt. Arthur. Results: herkogamy: 0 nun . 
Herkogamy measurements suggest this species is able to self-pollinate and does not require a vector to achieve 
poIlulation. It also suggests open pollillated plants will set unvarying high levels of seed under natural conditions and 
plants in low density patches will not be pollen lilllited. This suggests population growth is probably not seed linlited. 
CHR, 245 1 73, West of Cape Farewell, Wharariki beach, 2482-, 6078-, Druce AP, 1 971 ; CHR, 2778 1 1 ,  Northwest Nelson, 2474-, 6073-, Druce AP, 1 974; CHR, 285784, 
Northwest Nelson coast, sandhills creek, 2458-, 6059-, Druce AP, 1975; CHR, 295291, 1solated Hill, 25905, 59227, Wall A, 1930; CHR, 3 13 1 55, Northwest Nelson, north 
of Heaphy river, 2434-, 6024-, Druce AP, 1 977; CHR, 32571 0, Northwest Nelson, I mile south-west of Paturau river mouth, 246 1 -, 6061-, Druce AP, 1978; CHR, 387724, 
Northwest Nelson, Mount Hoary Head, 2493-, 6008-, Druce AP, 1980; CHR, 403757, Cobb Reservoir., 2483-, 601 1 -, Given DR 132 1 8; Given BB, 1 983; CHR, 405098, 
North-west coast, Sandhill Creek., 24586, 60592, Park GN, 1 975; CHR, 76086, West Coast south of Farewel! spit, Wharariki, 2482-, 6078-, Petters on lA, 1 954; CHR, 
87563, Mount Richmond Forest Park, Mount Rintoul, 25296, 59650, Gibbs FG; CHR, 159861, Above Cobb Dam, Lake Sylvester hut, 2479-, 6010-, Druce AP, 1 964; CHR, 
187736, Northwest Nelson, Top o/Mount Arthur, 24833, 59988, Ritchie lM, 1 970; CHR, 191 796, Mount Arthur, ridge/rom Flora Hut, 2486-, 6001-, Ritchie lM, 1 969; 
CHR, 1 97030, Nonhwest Nelson, Gouland downs, 2455-, 6033-, Druce AP, 1969; CHR, 208224, Mount Arthur, 2483-, 5998-, Brereton JA, 1 971; CHR, 223074, 
Richmond Forest Park, Mount Starveall, north o/point, 2530-, 5971-, Given DR 71549, 1971; CHR, 227637, Mount Owen, 2471-, 5961-, Simpson MJA 6672, 1 972; CHR, 
249602, Mount Owen, 2471-, 596 1 -, Druce AP, 1 972; CH.R, 261 786, Coast near Big River mouth, 2042 1 ,  54259, lohnson PN, 1 973; CHR, 269153, Mount Peel, 2475-, 
6007-, Talbot H, 1 948; CHR, 273514, Northwest Nelson, Cobb Valley, 2474-, 601 1 -, Druce AP, 1 974; CHR, 273843, Northwest Nelson, Mount Patriarch, 2468-, 5976-, 
Druce AP, 1 974; CHR, 274161 ,  Northwest Nelson, Cobb Valley, 24744, 60124, Haydock K, 1974; CHR, 277570, Northwest Nelson, Mount Arthur Tableland, 2480-, 
6001 -, Druce AP, 1975; CHR, 278288, Gouland Downs, Big River, 245-, 603--, SimpsonMlA, 1973; CHR, 28306 1, Northwest Nelson, near Boulder Lake, Orator Creek, 
2473-, 6033-, Druce AP, 1 976; CHR, 283086, Northwest Nelson, Boulder Lake, 2474-, 6034-, Druce AP, 1 976; CHR, 283749, Mount Ricrunond, 2543-, 5970-, Webb Cl 
7498; Webb TH, 1974; CHR, 285634, Northwest Nelson, Luna Lake, 2465-, 5977-, Dnlce AP, 1974; CHR, 3 1 0484, Northwest Nelson, above Lake Aorere, 2453-, 60 16-, 
Druce AP, 1 977; CHR, 3 10560, Northwest Nelson, Mount Domett, 2452-, 6015-, Druce AP, 1977; CHR, 3 1 1 79 1 ,  North West Nelson, Cobb Valley, 2474-, 601 2-, Druce 
AP, 1 977; CHR, 3551 37, Northwest Nelson, Matiri range, head of Bay creek, 2452-, 5953-, Druce AP, 1 979; CHR, 3551 39, Northwest Nelson, Mntiri Range, head of Bay 
Creek, 2452-, 5953-, Druce AP, 1979; CHR, 358525, Northwest Nelson, Garibaldi ridge, 2460-, 5996-, Druce AP, 1980; CHR, 387645, Northwest Nelson, Lockett Range, 
Mount Lockett, 2477-, 60 14-, Druce AP, 1 982; CHR, 38908 1 ,  Northwest Nelson, South Arthur Range, Mount Patriarch, 2468-, 5975-, Druce AP, 1 982; CHR, 40104 1 ,  
Northwest Nelson, Douglas range, 2472-, 602 1 -, Druce AP, 1 964; CHR, 401 063, Northwest Nelson, Anatoki range, 2478-, 6028-, Druce AP ,  1 984; CHR,  5 1 0682, Matiri 
Range, Haystack, 24539, 59558, Ford KA MlIO, 1 994; CHR, 76093, Gouland Downs, 245--, 603--, Gibbs FG; CHR, 76994, Mount A rthur, near saddle/rom Gordon 
PyramId, 2483-, 6000-, HayJA, 1 952; CHR, 77000, Northwest Nelson, Mount Arthur summit ridge, 2483-, 5998-, HayJA, 1952; CHR, 87755, Gouland Downs, 245--, 
603--, Talbot H, 1 956; CHR, 93441, Cobb Valley, Lake Sylvester, 247--, 601--, SimpsonMlA, 1957; Authors records: Balloon, 24785, 60044; Kakapo Peak, 24724, 
60204; Mt Arthur, 24833, 59987; Balloon, 24784, 60044; Mt. Patriarch, 24710, 59777; Kaihoka Beach, 24755, 60737; Hoary Head, 24935, 60076. 
1 64 
Endemicity: N.z. 
Reproduction: S 
Typical population size: S 
Threat status: None 
Main and lower: BS;  Top: A WR 
g 
0 
• 0 
<9 
0 
(iI 
0 
� 0 0 8 !iJ it 
o 0 
� Mt Arthur 
08$ 
oMt Owen 
Distribution records 
(accuracy) 
• CRR ( 1 00 m) 
0 CRR ( l  km) 
• Autbors ( l OO rn) 
CRR ( 1 0  km) 
- Dun Mt 
• 
0 0 
• 
. Red Hil l  
· St Arnaud 
o 1 0  k m  
1 6 5  
Myosotis australis R. Br. 'yellow' 
Ranking: None 
Abundance and Distribution: Disjunct distribution, central North Island and top % of South Island 
Habitat: Alpine, fertile substrates, rock ledges, stable screes, bare rocky pavement, growing in very little soil 
Threats: None 
Distinguishing features: Plants usnally consist of a single rosette, the leaves of which have fine, crowded spreading 
hairs that are sparser and retrorse underneath. The inflorescence elongates throughout flowering as flowers open 
sequentially. There are usually not more than three flowers open at any one time on each inflorescence. Flowers are 
yellow, unscented, tube blossoms with anthers and stigma included within the tube. 
Plants can be distinguished from M. a. ' small white' only with flowers. Plants can be distinguished from M concinna 
by their tube blossom flowers with very short filaments, and rosette leaves which have a good covering of fine hairs that 
are not appressed. 
Reproduction and recruitment: Study site: Mt. Patriarch. Results: herkogamy: O .  
Herkogamy measurements suggest this species i s  able to self-pollinate and does not require a vector to achieve 
pollination. It also suggests open pollinated plants will set unvarying high levels of seed under natural conditions and 
plants in low density patches will not be pollen limited. TIns suggests population growth is probably not seed limited. 
CHR. 285305. Mount Patriarch, 2468-. 5976-. SimpsonMJA 7391. 1974; CHR, 273792. Mount Patriarch, 2468-, 5976-, Druce ,AP, 1 974; CHR, 2738 1 7, Northwest 
Nelson, North East of Maunt Patriarch, 2469-, 5977-, Druce AP, 1974; CHR, 365448, Northwest Nelson, north west of Maunt Benson, 2472-, 601 5-, Druce AP, 1 980; 
CHR, 387429, Gardon Range, Gardon's Knob, 25048, 59552, Reid JS, 198 1 ;  CHR, 387668, Northwest Nelson, Lockett Range, Mount Lockett, 2477-, 6014-, Druce AP, 
1982; CHR, 393766, Northwest Nelson, Turks Head Range, 2468-, 5966-, Druce AP, 1 983; CHR, 401 654, West of Ricrunond Range, Gordon Range, 2506-, 5956-, Druce 
AP, 1 985; CHR, 87803, Mount Robert, 2494-, 5930-, Moore LB, 1956; Authors records: Mt. Patriarch, 24689, 59765 
166 
Endemicity: Central N. Is & S. Is. 
Reproduction: S 
Typical population size: S 
Threat status: None 
Left: A WR; Right: BS  
o 0 
. Mt Arthur 
o 
· Mt Owen 
St Arnaud� 
o 
Distribution records 
(accuracy) 
• CHR (IOO m) 
o CHR ( l  km) 
• Authors ( 1 00 m) 
o CHR ( l O km) 
· Du n  Mt 
. Red Hi l l  
o 
1 0  km 
1 67 
Myosotis australis R. Br. 'small white' 
Ranking: None 
Abundance and Distribution: This species is found throughout the Nelson region and its distribution extends across 
to Marlborough. It is  known from many sites and is usually sparse. 
Habitat: High fertility sites, forest -low-alpine, dry sites, under overhangs, able to tolerate low light levels 
Threats: None 
Distinguishing features: Plants usually consist of a single rosette, the leaves of which have fine, crowded spreading 
hairs that are sparser and retrorse underneath. The inflorescence elongates throughout flowering as flowers open 
sequentially. There are usually not more than three flowers open at any one time on each inflorescence. Flowers are 
small, white, unscented, tube blossoms with yellow scales. Anthers and stigma included within the tube. 
Plants can be distinguished from M. a. 'yellow' only with flowers. Plants can be distinguished from other small white 
flowered species by rosette leaves, inflorescences and habit e.g. Plants can be distinguished from M. forsteri by their 
leaf hairs which are short, stiff and sparse on the upper surface and not retrorse underneath in M. forsteri; plants can be 
distinguished from M. spathulata / tenericaulis by their spathulate leaves with well defined petioles and appressed hairs 
on both sides of the rosette leaves as well as tlleir prostrate, bracteate inflorescence. Plants can be distinguished from 
l'vi pygmaea by their prostrate habit, prostrate, bracteate inflorescence, broad petioles and absence of hairs on the 
undersides of their leaves. 
Reproduction and recruitment: Study site: Lake Peel. Results :  herkogarny: 0 mm. 
Herkogamy measurements suggest this species is able to self-pollinate and does not require a vector to achieve 
pollination. It also suggests open pollinated plants will set unvarying high levels of seed under natural conditions and 
plants in low density patches will not be pollen limited. This suggests population growth is  probably not seed limited. 
Cl-m.. 1 92301 .  Northwest Nelson, Pikikuna Range, Canaan Road. 2500-, 6027-, Druce aP, 1 969; CHR, 208221, Mount Arlhur district, near turnoffto Salisbury Hut on 
Flora track, 2483-, 6004-, Brockie WB, 1 969; CHR, 227664, lv/oun! Owen, 2473-, 5964-, SimpsonMJA 6699, 1972; CHR, 227666, Mount Owe�, Granity 
Pass, 2473-, 5964-, SimpsonMlA 6701, 1 972; CHR, 227730, Mount Owen, 59(;1-, SimpsonMlA 6765, 1972; CHR, 249594, Owen, Granity Pass, 2473-, 5964-, 
Druce AP, J 972; CHR, 249597, Owen foot of Billy Knob, 2474-, 5966-. Druce AP, 1 972; CHR, 249692, Owen Blue Creek, 2473-, 5966-, Druce AP, 1 972; 
CHR, 269137, Mount Peel, 2475-, 6007-, 1 948; CUR, 269138, Mount Feel, 2475-, 6007-, Talbot H, 1948; CHR, Mount Peel, 2475-, 6007-, Talbot H, 
1 948; CHR, 269140, Mount Feel, 2475-, 6007-, Talbot If, 1 948; Cl-rR, 277552, Northwest Nelson, Mount Arthur Tableland, Rock Shelter, 248 1 -, 6003-, Druce AP, 1 975; 
Cl-rR, 277571 ,  Northwest Nelson, Mount Arthur Tableland, 2479-, 6001-, Druce AP, 1 975; Cl-rR, 277743, Flora Stream, north of  Mount Arthur, 2484-, 6003-, Druce AP, 
1 975; CHR, 278315, Luna 2465-, 5977-, SimpsonMlA 7379, 1974; CHR, 3 1 1 649, N orthwest Nelson, Anatoki Range, 2478-, 6028-, Druce AP, 1 977; CHR, 
3 1 1 775, Northwest Nelson, 2474-, 60J J -, Drucc AP, 1 977; Cl-rR, 324222, Northwest Nelson, Luna Lake, 2465-, 5977-, Druce AP, 1974; CHR, 324223, 
Northwest ]\elson, Near Mount 2470-, 5977-, Druce AP, 1 974; Cl-rR, 355062, Northwest Nelson, Matiri Range, east of Mount Misery, 2451 -, 5961 -, Druce AP, 
1 979; CHR, 355063. N orthwest Nelson, Matir! east of Mount 2450-, 5960-, Druce AI', 1 979; Cl-rR, 3 55068, Northwest Nelson, Matiri Range, 2452-, 5 957-
, Druce AP, 1 979; CHR, 3551 36, Northwest Nelson, Range, head Creek, 2452-, 5953-, Druce AP, 1 979; Cl-rR, 355238,  North West Nelson, Matiri Range, 
24500. 595 14, Druce AP, 1 979; C HR, 358437, Northwest Nelson, Garibaldi 2461 -, 5996-, Druce AP, 1 980; CHR, 3 58438, Northwest Nelson, , 2461 -, 5997-, Druce 
AP, 1 980; CHR, 358479, Northwest Nelson, Garibaldi Ridge, near Sandy Peak, 5996-, Druce AP, I no; CHR, 365443, Northwest Nelson, South East of Mount 
Benson, 2474-, 601 3-, Druce AP, 1 980; Cl-rR, 3661 78, Northwest Nelson, Maliri Range, Mount 2449-, 5960-, Druce AP, 1 98 1 ;  Cl-rR, 387140, Northwest Nelson, 
Allen Range, Mount Zetland, 2449-, 5978-, Druce AP, 198 1 ;  Cl-rR, 3 8782R. Northwest Nelson, Range, 2476-, 6019-, Druce AP, 198 1 ,  CHR, 393798, Northwest 
Nelson, South Arthur Range, Mount Olive, 247()-, 5990-, Druce AP, 1 983; Cl-rR, 401004, Northwest Nelson, Anatoh 2478-, 6027-, Druce AP, 1 984; Cl-rR, 
401367, North Westland, Victoria Forest Park, Blue Grey River, track to Lake Christabel, 244]-, 5865-, Macmillan B H  Woods EH, 1 988;  CHR, 401 537, Richmond 
Range, Mount Riley, 2568-, 5977-, Druce AP, 1 989; Authors records: Gridiron Ck, 24841 .  60036; Dry Rock, 24814, 60032; Lake Peel, 24767, 60068; StaIrcase, 24737, 
59665 
168 
Endemicity: Northern S. Is. 
Reproduction: S 
Typical population size: S 
Threat status: None 
All photos :  A WR 
o 
a9 
o 
o • 
6 0  
o 
o 0 
8 
o o 
o 
<;0. 
t' 
o>Qo<? 
. Mt Arthur 
o Mt Owen 
Distribution records 
(accuracy) 
• CHR ( lOO m) 
o CHR ( l  km) 
• Authors ( l OO m) 
CHR ( 1 0  km) 
' Du n  Mt 
. Red Hill 
• 
o 
- St Arnaud 
1 0  km 
169 
Appendix  2 
The reproductive biology of Myosotis oreophi la :  a short report for A lan  
Mark and Katherine Dickinson 
Andrea Brandon 1 
Ju ly 2000 
I ntroduct ion:  
Long  te rm mon i to ring of  t he rare,  h igh-alp i ne Dunstan Moun ta ins  endem ic .  Mms( ) l;s 
or('( )ph i/o.  has round l arge fl uc tua t ions  in populat ion  dens i t y  and s i ze .  have occmred 
d u ri ng t he study period ( S tan ley  el 0/ . 1 998 ) .  Permanent  p lo ts  were es tab l i shed at t he 
-; i t c  o r  t he on l y  k nown popu lat i on to co l lect  demograph ic  data .  wh ich .  s i nce I l )ln .  h � IS 
i l l c l uded such add i t ional  i n format ion as flower bud i n i t i a t ion ,  i n flo rescence numhe r  per 
p l �l n t  and !"l owering i n tens i ty  ( S tan ley  el 0 / . 1 998 ) .  Stan ley  et 0/ . ( 1 998 ) round  t ha t  
wh i le t hese !" loweri ng  characte r ist ics varied over t he fi ve year  pe r iod or  t hc 
demograph ic  st udy.  they fou nd no obv ious re l at ionsh i p  to  p lan t  recru i tmen t .  Popu la t i on  
g rowt h does no t  appear to  be  affected by any  aspect o f  sexua l  reproduc t ion .  The  
v, l r ia t ion  i n  p lan t  dens i t y  was  t hough t  to be re lated to env i ronmenta l  fac tors s l Ich  as  
w i nd exposure and  snow l ie cond i t ions  ( S tan ley  el of .  1 998 ) .  
ew Zealand MmSOI;s spec ies  s tud ied to  date fa l l  i n to e i t her  one of  two  pol l i l l ,l l i on  
synd romes based on  t he degree of herkogamy exh ib i ted by t he flowers.  Each s pec ies  
e i t her  req u i res a vector to ach ieve po l l i na t ion  or  i s  ab le  t o  se l f-pol l i nate autonomoll s l y  
( B randon and Robert soll . i n  prep a ) .  Those spec ies  t hat  req u i red vectors to ac h i eve 
pol l i nat ion  have a l l  been found to s u ffer A l lee effects  i n  t haL t he i r  seed p roduc t i on i s  
d i sproport ionat e l y  affected b y  l ow loca l  dens i t y  ( B randon and Robertsoll . i n  prep b )  I n  
order t o  dete rm i ne whether  reproduct i ve e ffort has a n y  e ffect a t  al l o n  t he dernograph ics  
o r  t hese rare p l an ts. pol l i na t ion  requ i rements  need to be  understood . There i "OI"e . t o  
determ i ne pol l i nat ion req u i rements  a nd  poss i b Je dens i t y  dependence for seed product ion  
1 Fund ing  p rovided by M i ss E.L .  Hel l aby Trust  
1 70 
I n  NI. o}"cophila .  the  northern Dunstan Mounta i n s  popu l at i on was s tud ied dur ing  t he  l ast 
season .  
Methods: 
Population: F i eldwork was carried  out at the o n l y  known loca l i t y  for t h i s  
h e  N orthern Dunstan Mounta i n s  (G4 1 .  465 87 1 .  1 640 m ). i n  Fehruary :?OOO ( 
I II 
I l . 
Fig,un' I :  Location of d i ,tr ihution or /'v1msll l is  ore()jl il ii(/ . l tl the northern Dunst<ln \10UI1Ll ln" .  
( 'L' J 1 t r,d ( Sou th  I s land.  
: j \l' p l an ts  w i t h  u nopened buds were caged to exc lude pol l i nators .  Nlat uri ng  cl l \ ce:-,  
\\ ere lected subsequen t ly  and  resu ltant seed se t  recorded.  Th i s  was  t hen  to  
\eed  se t  u nmanipu l ated. open  pol l i nated p lant s .  Herkogamy was measured llslll g 
I pe rs . Seed set coun t s  were made on open po l l i n ated p lan ts  for wh ich  loca l  t1 ( )wer 
dens i ty  was recorded to determi ne whether  l oca l  rlower dens i ty h as any i n fluence on 
product i on .  
1 7 1  
Data analysis:  
seed set  data were analysed uS l l1g S'-PLUS', The proport ion  or  
compared hetween pol l i nator-excluded flowers and  those i n  open  Ions .  
x am i ned the  effect  of l ocal  flower dens i ty  on  seed p roduc t ion ,  
Results and  d iscussion:  
IvIVosotlS oreophlla 
() Cl  i 
0 4  
Po!l iflator excluded 
Treatment 
Unmampulated 
Figun: 2: Bm:pl ( ) t  ( l l  re,u l l an l  seed lrom the  pol l i na tm exc l uded 
Ana ly s i s  of Variance Table  
I 
( I eft l and t hat ( l l  
Response :  asprop  I as i n  t ransformat i on o f  the  mean proport ion  of  ovu les per t hat 
set seed per p lan t )  1 
Terms added sequent i a l l  y ( first  to las t )  
DI  Sum 01 Sq  
Treatment  O .K l)/\ I K42 
Residuals  
Mean Sq 
( ) Kl)/\ l K42 
O.02..:f650l) 
F Value Pr( l '  ) 
..:f . ..:f 7 II7%c-( )( )h 
1 7 2 
Herkooamv ,.., " 
Taille I :  
P lan t  
, 
+ 
" 
il 
� 
rllCasurcll cn ts 
H crkogalllY ( mill ) 
( ) l) I .') 
0 . 0  ( ) 2 
() } ( ) 2 
( ) . s  U 
0.0  0 .6  
1 .+ I .') 
( ) O 0 .2 
0 0  0.0 
���--�--��-
O B  : • 
• 
• • 
• • 
0 .2  
o 
• 
• 
5 
Myoso/IS oreoplllia 
1 0  
• 
• 
1 5  
Flower denSity per mi 
1 4  
0 .0  
0.0 
1 ' 
0 .1\  
1 . 2 
0 .1\  
0 ]  
Figure 3 :  Scattcrp l ot or  sccd product ion aga ins t  l ocal  flower dcns i t y  
1 , 
1 . �I 
1 . 1  
20 
Ana lys is  o f  Var i ance Table on un transformed data  
Rcsponse:  asprop  
Tcrms added sequen t i a l l y  ( fi rst t o  l ast ) 
Dr  SU Ill or  Sq  Mcan Sq F Val uc Pr( F )  
rlowcr  dcns i ty  
Rcsic l ua ls  
0 . 0  I 05605 0.0 I 056049 0 . 2 836924 0 . 60 I I X47 
1 7  0 . 63 28274 0.03 7225 1 4  
Ana lys i s  o f  Var i ance Table o n  l og t rans formed flower dens i ty  data  
Rcsponsc : asprop  
Tcrms added sequent ia l l y  ( fi rs t  to  l ast ) 
Dr SUIll or Sq Mcan Sq F Va l uc Pr( r - )  
log lO ( rJowcr dcns i ty  0.0072 3 9 3  0 . 00723925 0. 1 9 34568 0. 6655956 
Rcs idua ls  1 7  O.636 1 4X6 ( l .03 7.+205 I 
f\ na lys is  o r  Var i ance Table on polynom ia l  t ransformed flower dens i t y  da ta  
Response : asprop 
Tcrms added sequent ia l ly  ( fi rs t  to  l ast ) 
Dr Sum  or q Mcan Sq F Valuc Pr( F )  
-_ .. ------------------------ ._-_ ..... _-_ .. . .. _ ......  
Polynomia l  ( !lowcr dcns i ty .  2 )  2 
Rc� id Lla l s  1 6  
0.0267 349 ( l .O 1 3 36746 
0 . 6 1 66529 o.m 5.+0, I 
O.3.+6XYJ I 0 . 7 1 2 1 0-1 2  
Po l l i nator exc l uded p lan ts  set  s ign i fican t l y  l ess seed t han  opcn pol l i nated p l an t s  
( P<O.OOOO I ) . Average seed set  for pol l i nator exc l uded p lan t s  was 0.7  seedsmowc r . 
A verage seed set ror open pol l i nated p l an ts  was 2 . 25 seedslflower.  Seed product ion  i �  
s ign i fican t l y  a ffccted by  t he exc l usion of  pol l i nator serv ice .  Herkogamy was \ ' � l r i ah l c  
w i t h i n  p l an ts  sampled. flowers of some p l an ts  were always herkogamous .  bu t  ot hcrs 
were less cons i s ten t .  Measurements ranged from 0.0 to 1 .5 mm.  Loca l  dens i ty  had no 
e lTect on seed se t  by  open pol l i nated p lan t s  us i ng untran s formed da ta .  Nc i ther l og 
t ransformat ion nor  a pol ynomia l  t rans format ion  of flower dens i t y  made any d i fference .  
Seed set resu l t s  ra i l  i n  between t he two ex t remes of t he pol l i nator-requ i ri n g  t ype such as  
Mmsotis /JIO/ l roi  and t he se l fi ng type such  as M. fo rs/eri ( see Table 2 ) . 
1 74 
Tahle 2: Average seed sel by olher spec ies  I'or comparison ( max imum seed sel per nOlVer is -+ )  
Spcc ics  
M. orcnph i l a  
M . l l lonro l  
M.  I 'orsteri  
Number of seeds set per !lolVer 
when  pol l i nators are exc l uded 
( means ) 
0 . 7  
n. 1 6  
3 . R  
Number of secds sct pcr flowcr Iw 
unman ipu latcd p lan t s  ( I l lC�l n s )  
._--- _ ........... _ .. _-_ ...... _ . _ ... __ ....... _ .. _ ......... _. 
2 .25  
1 .5 X  
T h e  m e a n  n u m ber o f  fl o w e rs p e r  i n fl o re sc e nce i s  9 . 5 .  T h e  m e a n  n u m be r  i n fl ore sce n c e s  
p e r  fl o w e r i n g  p l a n t  i s  3 . 2 .  T h e re fore, average s e e d  p rod u c t i o n  pe r rJ owe r i n g  p l , l n t  
wou l d  b e  6 8 . 4  ( i . e .  2 . 2 5 * 9 . 5 * 3 . 2 )  for ope n pol l i nated p l a n t s .  I n  t he worst case sce n a r i o .  
i r  n o  e x t e rn a l  pol l i n at i o n  occurre d .  a v e rage seed prod u c t i on p e r  fl o w e r i ng p l a n t  w o u l d  
h e  2 1 . 2 8  ( i . e .  0 . 7 * 9 . 5 * 3 . 2 ) .  S t a n l ey el 0/. ( 1 99 8 ) report res u l t s  rrom a ri ve y e , l r  
de mograph i e  st u d  y wh i c h  est i m ate t he t o t a l  n u m be r  o f  p l a n t s  i n  t he popu l at i o n  ha ve 
ra n ge d  rro m abou t 1 3 .000 t o  2 1 , 8 00 p l a n t s  ( ad u l t  and j u ven i l e ) d u r i n g  t h e st u d y  pe r i o d .  
T h e refore . seed produc t i on does not appear t o  b e  a l i m i t i n g fac tor ror popu l a t i o n  g ro w t h  
o f  t h i s  p art i c u l ar l y  loc a l i zed rare p l an t . I n  order t o  be cert a i n .  seed au g m e n t a t i on , t nd  
i n t ro d uc t i o n  s t ud i c s  cou l d  b e  c a r r i e d  o u t  to determ i ne w h e t h e r  o r  n o t  t he g ro w t h or  t h i s  
popu l a t i o n  i s  seed l i m i t e d .  
H e r ko g a m y  m e a s u re m e n t s  con fi r m  bot h vect or-re q u i r i n g  a n d  a u to nomou s l y  se l t"i n g  
n o w e r  I l l o rp h o l o g i e s coe x i st w i t h i n  t h e  s a m e  popu l a t i o n  a n d  w i t h i n  t he s a m e  p l a n t .  
Po p u l at i o n s  o f  p l an t s  w i t h  m i x ed m at i n g syst e m s  c a n  b e  a t  a n  adva n t age i n  c e rt a i n  
c i rc u m s t a n c e s .  I n  hars h e n v i ro n m e n t s ,  s u c h  a s  at t h i s  s i te i n  t h e h i g h  a l p i n e zone 0 1' t h e 
D u n s t a n  M o u n t a i n s ,  po I l i nat o r  av a i l ab i l i t y  w i l l  vary s u c h  t ha t  w he n  con d i t i o n s  , I re 
s e v e re .  s e l fi n g  i nd i v i d u a l s  may be t h e  on l y  p h e n o t ypes rep rod u c i n g .  H o w e v e r .  a 
po s i t i ve fee d back loop c an est a b l i s h ,  as seed p roduct i o n by s e l f- po l l i n at i n g i n d i v i d u ,t 1 s  
i s  ge n e ra l l y  h i gh and c o n s t an t ,  l e ad i n g t o  i m proved recru i t me n t  c h a n c e s .  A t  t i me s  w h en 
cl i m a t i c  c o n d i t i o n s  are fa voura b l e ,  a n d  popu l at i on dcmograp h i c s  a re s u ffi c i e n t  t o  a t t ract 
po l l i n a t o rs .  t he presence o f  o u t c ro s s i n g  phenotypes in t he pop u l a t i o n  Can t he ll he 
he n e fi c i a l .  part i c u larl y i f  i n breed i n g  depre s s i o n  is occ u r r i n g .  I n  fact t h e h i g h  , I n d  
c o n s i s t e n t  s e e d  p roduc t i o n  of s e l f-fert i l e p l a n t s  cou l d  a l low fo r con s i de rab l e  s e l ec t i o n  i n  
t h e  o ff- s p ri n g  w i t h out s h ow i n g  a n y  d e t e c t able e ffec t s  on d e m o g r a p h y  ( Lu i tj e n  et ( //. 
1 9 9R ) .  W r i gh t  ( 1 939 ) c o n s i de re d  s u c h  a s i tu at i on to be ad v a n ta ge o u s  to popu l a r i o n s  i n  
w h i c h  rep roduct i o n  i s  pre dom i n a n t l y  se l fi n g .  He c o n s i dered occas i o n a l  c ross i n g c o u l d 
1 7 5 
a l low for e ffect i ve se lect ion by genotypes i n  a "cont i nuous ly  restored fie l d  o r  
vC lr iabi l i ty" (Wr ight ,  1 9 3 9 ) .  The m ixed mat i ng s t rategy t he re fore a l lows Jlo Jlu l at i ons to 
pe rs is t  in  d i ffic u l t  c i rcumstances and then  t ake advantage of more favou rab le  cond i t ions  
when t hey OCCU l" .  
S t an ley  el o/. 's ( 1 998 ) conc l us ion  t hat env i ronmenta l  factors p lay an important ro lc  I n  
e x p la i n i ng t he fl uctuat ions  i n  t he demograph ic  parameters t hat  have been measured I n  
t h i s  popu l at ion  a r  t herefore supported . 
References : 
B randon . A .M .  and Robertson, A .W .  i n  prep a. Pol l i na t ion syndromes. herkogamy and 
rari t y  in  s ix  spec ies  of  New Zea land  MYOSOlis L. ( Borag i naceae ) 
B randon.  A .M .  and Robertson.  A .W .  i n  prep b .  A l lee e ffect s  i n  p lant  reproduct i ve 
pe rformance:  Loca l  dens i ty ,  popu l at ion s i ze. rar i t y  and reproduct i ve s uccess i n  
natura l  popu lat ions of  MV()SOlis L. ( Borag inaceae ) 
I _u ij t cn .  S . H . ,  Oosterme ijer, G . B . ,  E l l i s-Adam. A . c. and Den ij s .  H .C. M .  1 99R .  
Reproduct i ve biology of  t he rare b ienn ia l  Cell tiallella gemwll ic(( cOl l 1p � l recl w i t h  
other gen t ians  o f  d i fferen t  l i fe h i story. Act(( Bot. Need 47: 3 2 5 - 3 3 6  
S tan ley.  R.J  . . D ick i nson ,  K. J  . M .  and M ark.  A . F. 1 99 8 .  Demography  of  a rare enci em ic  
Mmsotis: Boom and bus t  i n  t he h i gh-a lp i ne zone of  sout hern New Zea l anci . 
A rClic ol/d A /pine Research 30: 2 2 7-240 
Wrigh t .  S .  1 93 9 .  Breed i ng  st ructu re of  popu l at ions i n  re l a t ion  lO spec iat ion . The 
Al I /ericolI N(( / l Iro lisl 74: 232-248 
I Hi 
Appendix  3 
Seed set by h and-po l l inated f lowers of Myosotis monrol at the two stages ,  
precocious buds (p )  and open f lowers (0) , 
Plant Sta�c Seed set OVIlIeS I'nportioll 
I () 1 O  I II 1 ) 625 
P x I h  (J 'i 
-' () 2 1  .� � 
jl -+ -1 I j 
.j () 7 k O S7)  
P X I ] O.666hh7 
'i ( ) -+ .j I 
P IJ 1 2  ( ) 7,,- ! r--c:--! () 1 1  \ 2 O tJ l hhl)7 
P X S ! I 
C) ( ) 1 1) 2()  O X  
P -1 1 2  () .3 .lJ .� . {3 
1 2  ( )  .<2 �() O .kS"SSC) 
I' 1 3  2 0  O h') i 
1 ,\ () 1 0  1 2  ( } . S33�33  
I '  () X 0 .75  
1-1 () 1 2  1 2  I 
! I' I .j � 
I h  () l x  .� D.:;()25 
I' I q  I� ! ( ) .j 7'i  
! 211 ( )  .\ .) I I 
p 7 X I ) .X7 .' 
2 1  (' h X I. )  2.:' 
p !) 1 2  1 1 7� 
y, ( )  1 0  I (, 0.1,2.' 
l' :; X 11(,]') 
n ( )  .j ./ I 
P !) 1 2  1)/"  
.:2 X () -1 .j I 
I' 1 1  1 2  11 ') 1 ()hil7 I 
i l ( )  1 6  I II I 
P 2 7  1. :2  ( J .S.j"7,)  
.1 2 () 1 .\ I 
r p 1 6  I h  I 
, i  ( )  2() � (j ')2 X'i 7 1 
Jl 1 2  2 ( )  i I .h 
\-+ () 1 1 I !() (1I!.2. 
p 1 0  I () I iJ .(,2.'i 
y, ( )  ! i () 1 6  I I 
I I I' .j X 1) 5 
JC c l  7 X I IX7 .' 
I' h 1 2  Il ,) 
""leans 
Appendix 4 
Po l len load on p recocious and fu l ly open f lowers of Myosotis monroi. 
Locat ion Pol l en  load on st igma at precocious phase Pol len load on stigma at end 01' male phase 
DS 0.00 75 .00 
I )S  0.00 71.00 
I )S 0.00 1 03.00 
J )S 2.0( )  52.00 
I )S 0.00 59.00 
I )S  0.00 64.00 
DS 0.00 1 02.00 
I ) S  0.00 0.00 
J ) S  ( l .00 H.OO 
I )S  0.00 46.00 
I )S  6.00 7 1 .00 
J )S ( l .OO 23 .00 
I )S  7.00 55 .00 
J ) S  0.00 5 1 .00 
J ) S  0.00 55 .00 
J ) S  0.00 5-100 
J )S 0.00 :l .00 
I )S 0.00 0.00 
J )S  o 00 -lOO 
DS 0.00 noo 
J )S 1 7 .00 1 04.00 
J ) S  1 6 00 7 1 .00 
J )S 0.00 4.00 
J )S 0.00 0.00 
CS ( LOO noo 
CS 0.00 0.00 
CS ( l .00 1 0.00 
CS 0.00 0.00 
CS 0.00 noo 
CS 0.00 42.00 
CS 2 .00 1 0.00 
CS 0.00 60.00 
CS 0.00 Y).OO 
S J) M  0.00 :lH.OO 
SDi\ l  I .00 I S .OO 
SDM I 0 00 noo 
SDi\ 1  ( LOO 6.00 
SDi\ 1  2 .00 42.00 
SDl'v l  :l.00 4 1 .00 
SDM 0.00 S .OO 
SDM  0.00 3 .00 
SDM 2 .00 :1 .00 
f )S = DUll Saddle:  CS = COpperll l l llC Saddle: SDM = Sout hcrn s lope, 01 DUll Mounta in  
I n  
Appendix  5 
Spec imens used for morphological  measu rements in  the  rarity i n  New Zealand 
Myosotis study.  
M. o ll/oldii: CHR 25 8649. CHR 25 8649, CHR 7 6 1 8 3 .  CHR  269 1 36.  CHR 474075 
M. { / l IgIISIOIO : CHR  1 87735.  CHR  3 8 7 640. CHR  2082 1 7 . CHR 295 297 
M. ((Iho-sericeo: CH R 4 1 6092 
M. (If{s!rolis 'yc l low' :  CHR 405 242. CH  R 405 242, CHR 3 87429. CH R 2 2 29 8 7 .  CH  R 49 1 7 4 5 .  CH R 
.� 67 2 1 .  CHR  40 1 654. CHR 6939 1 .  CHR  274737 
My(}'\ ( ) !i.l ol ls!rali. ' smal l  wh i IC ' :  CHR 2 7 8 3 1 5 . CHR 269 1 39. CHR 269 1 3 8 .  CH R 249692. CHR :1 1  1 77 '.  
/11 .  ' I  y l l c l l oncns i s' :  CH  R 479466, CH R 34495 I .  CHR 34495 I .  CH  R 1 78294. CH  R 4R045:1 
tII. hrnckiei: CHR  365506. CHR  3 1 1 7 22 .  CHR  3 3 5 754. CHR 1 7 1 679. CHR  3 1 1 7 1 7  
M. ( { {piww: CH  R 49642 .  CH R 4964 2 1 .  CH  R 308227 
M. c"eesell/ollii :  CHR  4759 1 9. CHR 4 7 5 9 1 9  
M. ( (illcillllO CHR  2497 1 R .  CHR  3 3 5 7 5 5 .  CH R  335756.  CHR 22766 1 
M. mlellsoi: CHR  97 296, CHR  2907 3 5  
M. elrleri CHR 5 6 7 3 3 .  CHR 22605 7 .  CHR 5 4 3 7 1 .  CHR 2 2 2 7 60. CHR 3 6059 
/11. ('xill lio: CHR  244028 .  CHR  6300 2 .  CHR  5 0 8 2 2 2  
M. CXpIOIlOlO : CHR 1 84602. CHR 3 2 8259 
M. /i ) { .I !l'ri: CHR 295 263. CHR 334803 . CHR  295 2 8 1 .  CHR 1 4637 1 .  CHR  3 5 5 1 76.  CHR Yi Wi 1 1 . C H R  
2-1633R .  CHR  3 23 7 8 8 .  CHR  3304 9 .  CHR  1 0 1 430 
11' 1. .�( J r('{ { ii :  CH R 30 1 7 50. CH R 878 I O.  CHR  4 3 9799 
M. I({( 'w: CHR  3 R7 3 7 6 .  CHR 387462 
M. l\(fllii v a r. /mllii CHR 6790 1 .  CHR  1 5 80 3 7 .  CHR  5 1 4986. CHR  22 3 9 3 2 . CHR  25 R95 X . . 
M l\(fllii var. f(!\ I 'IISOllii :  CHR  3 1 0505. CHR  3 8 7 1 35 .  CHR 3 8 7 1 36 
M. II{( {(roll !If ( { :  CHR  3 1 4470. CHR 3 7 1 665.  CHR  40 1 060. CHR  76066. CHR  1 09 5 3 .  CHR 27-+ I Y) .  CHR  
2 0 5 :2 6 1 .  CHR  269 1 49. CHR  76067. CHR  2 8 3 5 29. CHR 1 0 1 3 8 3 .  
'"  II/({llhe l l 'sii: CHR  -169640. CHR 46964 1 .  CHR 295 3 1 9, CHR  1 10255 ,  CHR 3 1  I no 
'" ( Jreopl/ilo: CHR  409 1 7 2 .  CHR 409 1 7 2 .  CHR  409 1 7 2 
/ 1 /. 1 I / ( ) l Iroi:  CHR  9 7 2 8 :2 .  CHR  603 1 9, CHR  3 87447. CHR 295249. CHR  295 249 
/ 1 /  pl' !iolmo var. pefiololCl :  CHR  87 8 1 1 . CHR  1 9 1 795 . CHR 2086 1 7 . 
/Il . pl' fiolmo var.  pm/.\{{ : CHR  56737 .  CHR  2 2 3568.  CHR  3672 1 2. CHR I X4602 . CHR  295 .\ 1 5  
M. I )(,fiolof{/ var .  pOllsiof/o:  CHR  367640. CHR  790 7 3 .  CHR 508 1 6 1 .  CHR  97 305 
M. I) { {h ·illoris: CHR  40425 I .  CHR 404363 
M. p rgll{{/(,o var.  p rgllweo: CHR  208826. CHR  277. CHR 1 3 1 076.  CHR  3 1 3  1 5 5 .  CHR  3 25 7 1 0. CHR  
3 8 7 72-1 .  CHR  309606. CHR 245 9 1 2 . CHR  308602 . CHR 1 096 1 .  CHR  567 1 2 . CHR  3 5 7: 1 70. CHR  
:1 0 :1 84,:( 
M p rgllf( {eo v' lr .  dmcei: CH  R 1 3 1 906. CH  R 1 9068 1 .  CH R 80 1 65 .  CH R 3 1  1 79 1 .  CHR  :207050. CH  R 
3 1 6 3 4 8 .  CH  R 364085. CHR  252 1 54 .. CHR  1 9703 1 .  CHR 249602. 
/1 1. p rgll/({(,o var. glollco: CH R 87808.  CHR  1 89272. CH R 567 1 8 . 
M. Ji."gll/oeo var . l I /ill l lfif7oro : CHR 243997 . CHR  473245 
M. mkillra:  CHR  3 1 274 1 .  CHR  1 77 64 7 .  CHR  283748.  CHR 2 5 3085 
M. SUW.I'o : CH R 8 7  I 33. CH R 245 866. CHR  2 1 0  I 1 4  
tII .l/lmll l l lmo: CHR  205 2 3 5 .  CHR 1 3 1 69 8 .  CHR  1 79627.  CHR  478284.  CHR  2 8 8-10 1 .  CHR 1 :29 1 1 5 . 
CHR  243992.  CHR  1 3 1 990. CHR  7606 5 B  
M. SIlO I 'i.l' : CHR 2 3 3 8 7: 1 .  CHR 1 66897.  CHR 2 8 1 096 
M. feI lNicollli.l : CHR  35464 1 .  CHR  269 1 5 8 .  CHR  2082 1 9, CHR  22 1 9 6 8 .  CHR  6 3004 
M. fml'erlii  var. cOllwlmco: CHR 1 09 5 5 .  CHR  3 2 8 2 8 8 ,  CHR  3 2 8 2 8 2 .  CHR  2 5 2799. CHR  2 5 2 8 ( ) 1  
M. fml 'N.I'ii var.  frol 'ersi: CHR  207 1 33 .  CHR  365454. CHR  2 2 5 89 1 .  CHR  20 1 499 
M llllif7om: CHR  2 5 2802. CHR  205 29 1 .  CHR  49932 6. CHR  1 49427 
M. l ·eIlO.lO :  CHR  1 65 798. CHR  1 3 1  1 75 a.  CHR  97303 . CHR  2 5 2 1 36. CHR  1 89 1 60.  
M. 'saxal i l  i s ' :  CHR  3 2 8265 . CHR 8 4608, CHR  3 87544. CHR 243 8 1 4. CHR  249 1 90 
1 7 9 
Appendix 6 
S p e c i m e n s  of Myosotis fors teri and M. venosa from which measu rement  data were taken ,  
I I\II" '/ : I  ! I / i l "ii C I I I, ]�L'�H ).:' , ( ' 1 1 1, I � () I (' I ). ( ' I I R  1 ( 1 1  e l m  I " ( I l l{ C(,I I(" ( ' 1 1 1\ I CJ! !') C .'i . 1 ' l l I< 2 .:' :' 1  ,I, ( ' 1 1 1\ 1 (,:' "'1·). ( ' 1 1 1< '1" ,0., .  ( ' I l l' 1 (, :' Clj,\ 
) I I I I S ,\ I )  (l I R  hl! i l  C I I I< '.:i I)il(lj ,  C I I I<. ' C I I I, 1 1 1 ( l I ( I { 'I /I 'II \1 1{ C I I I' .'i7(, " i, CII R 7 C I I I! S;(J I I )  C I IR Pil i  I ,S. ( ' I l l' I ( ' 1 1 R 2q:' .'r,\) (, 1 1R 1 '9:'('l i , (l 1R 2 1 1 .' i ( ) C I IR :'�I·I:'(,.\ . ( · 1 1 R  I '! I  ( ' 1 1  
2�2:''J-+. C H R  1\\ 1 0\1:' ,  CHR ,'!, 1 ,+ \  CIlR  2 1 i 1 1  �� , \ .  CIlI, 27�2 '\(" C I lR ' l :i7%, C H R  21)Sld l. Cl IH SOl  hX. ( 'H I{ 1 1 1 )' ,,\ Cl iP 2 1i'2S I C l  \ \{ .'xil ! ) ' .  ('H R ' \ \ 
.'S'l-+xo. CIlR YOlx5 1 1 .  (,I I R  -+110.,') 1 ,  C I l R 2 , 1 :'(,:'. ('HR  2 1 1 0 :' 2  Cl 1 1<. 5 1 .; 2 .' 1 1 ; .  C Il R  1 () I �L'iI el m sr._ ' CIIR I I JI!.'''. I'tIR CliP  .' lh.'XIl, CI I F  2 H,.1 
.'11. C lm  2l):i2h'  nm 2CJ :i22�L CHR \)·11 1 1 ' (' Il R 
�. ( ' I l l' ., '5 1 76.  CI I l{ 1 �57S:' .  CHR 'xO I I .  (, I I R 1 1 .,-+72 .  
[ahlc , 1\,,\, data 
Specie" typl' 
\ '"-'11 0 <.:.a 
I S'l I ()II \ ('no<.,a 1 (, 10 '::5 0 .7  � .X  1 �5 h . . � I �5 2 . 2 .� 1 . 2 "  x . 2x  1 25 7 %1:;7:' bd,,,, scaic" c ia, at" 
1 3 1 1 7 .:1 \ cno:--a 1 0 I '  �3 IUS I ·I " 1  2. 1 l.; 1 25 h . 1 25 , I h.flq," 75 6 .:')h25 at scak, clavate 
\ .")21)2.\ \ \.'no�a .19 I S  .)-+ I ) �r .ilh2 :'  7 2 )  7 (1.:'h25 7 );;)25  ;)1 ... c a le." c la\  ale 
7h06.1 \ cn()sa 1 2  IJ I :'  0)7 1 -+29 2 . ( ).� I 2 :::; 7 1 2 � ! . ))75 7 x l  l) .)'Xq ) at :--caks l'lalatc 
1 '!()lJ75 \ l' lHy .. ,a I ' 1 1  1 11 I ) 7 .� .2 . 0 1 .?5  LOh:?:,) h . I S  h U'J.;7:i hell)\\ .... cale" c la' ale 
.:?5.:? 1 3h \ cno....,,, 1 (, 1 1  2 )  () ) 2 J<:;() 25 + .625  [ . h25  h i l9 n 'i (l.5(125 hell'" -"l'al('\ capitate 
1 65799 \ l'nosa ,'9 I X  ;-+ ()  7 1 ·12i\() , 1 2.:' :' .(r� 7:1 1 . . :'(,2.'1 � '- + .-:; 75  a t <.,cak:-. capitatc 
'!710\ \ l'l1OS11 2 1 I �  25 O.h2 ! h�2 ' 0 . ,  I h 7 ,'i I :I().':' � . 1 25 K . 7 ';  at ,cale, c\'lI ate 
I h579K \ CIlOSa -+ 1  20  �f·4 () h.;.�.;.�.-:; .2 h:'\()25 h 1 1) :'  S 2("-) ! 2:'  7 .%i:)( 5  al <.,cak" ,'apilnlC 
K7(),1,9 fUf-.,tcri I () 1 0  :2 � l) h(J�()lJh I ( .�) :' 4 3 7 5  I 2)  1 2.'i 5 l).1,75 I",\(", ,<.,cah::- c la\ aIL' 
7 .�7)� j"\)\'\lcri 2-+ 1 6  25  i l ,:' I 5h�5 �i .�  I 5 7S 1 25 !) O'! , 7 5  a t  ..,.:ak:" dll\ \\tc 
S7(,,·10 rn r'-.1 cri h , :' �I () .:'()2'i I (l'l.n, ' ·n7" ( L9.1 ,75 K-I 'l'  ) .  ! )()2:=-:  bellh\ "cdc" dd\ ;J(c 
�i76 1 I K  fm'lni 25  211 2X 0 .6 ) 1 .� . 75  ( )  9?,7::" (,. ':: 5 h .:2)  hdo\\ "cak'." ,'ap; !;)!c 
1 )l',lJ7 7  f()r�lCri ,7, 2 1 7  J )  (l (, 'i . 1  O S  1 25 q O(,2, � . I helll\\ '"(ak,, Capliah:' 
2952h'! fO!,,,tLri 1 2  () 20 ( )  .'i�L'i-l.'i5 , S )  � :� ·f ( )  K 1 25 � 5 .h25  , hd(l\\ "l'ak� c la\ all: I 1  
1 .'il)21J1l Inr\/cri .1' I q  I I  h i  1 1  I I 1 1 25 IUS  ( ) I) , .:i hL' II. l \\ "l'alc" cl:n alc 
) 1 1 .1,3( ) ! I ) !'\k'r! i 2  ! )  )·-1-::; .. � 5 ."\ I 5 ( )  .. �5  ( ) , " { } . i )\)Y75 hcJcl\\ ",-'a h.' " ,'apl latc 
2�)-+2(' 1  f\)r-,tcri ().j �( ) ( ) , () hi;7�  ! I  hclo\\ ",-'all'" eLI\  '-I\<..' 
l xO 
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.' 119-180 
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.'-\('.'(;h 
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l l lf'" I\.'l"l 
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I ( l l''-.k'rl  
rnr,,1cri 
ror, [cri 
i or'-.lL'ri 
rnr�tcri 
iorslcri 
j pl"'-,lcn 
l'nr"k'ri 
r{)r�tcri 
1'or"lcl"i 
fUI"<.,lcri 
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forqcri 
i(lrqcri 
illrstcri 
forstcri 
fnr...:;tcri  
rpr\lcri 
forskri 
fur"1cri 
rp\"\\cri 
forsteD 
rorstcri 
forstcri 
rorc.;kri 
\'\If'-.\,>-'ri 
rnr-,kTi 
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hel' 1\\ "L'ah.:'-.. 
hL'l\l\\ "L'ak" 
/ 1L'lu\\ '-..\:�d,--' '-.. 
hel,)\\ "c�dc" 
hL' !n\\ "cafe" 
hdD\\ 'lLa\(:" 
he[o\\ ".caiL'" 
hc!o\\ "calc" 
hdo\\ :--.calc" 
belo\\ \cale" 
bdo\\ \calc" 
hc1u\\ \cak'\ 
belcm scail's 
bc1o\\ scaks 
hdo\\ scales 
helow scales 
hell'" sca1cs 
hell) \\ \cale" 
bc1\)\\ \cait.::s 
bclcm scalc, 
beloll scales 
at '-..l'alc<.; 
belcHI scales 
bellm scalcs 
hclo\\ "calcs 
bclo\\ ,;calcs 
hcll\\\ \,cak'\ 
hL'i{)\\ "c�!k" 
he],)\\ ",:ale" 
1 \  pc' 
l' d p l l ; l lL' 
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(apilatc' 
cla\ alc' 
capl l<llc 
cla\ alc 
-:apitak' 
capltale' 
c ia'  <llcl 
c lal all' 
capitate 
c la'a lc  
Capi(ale 
c l <l'ale 
cia, ale 
capitall' 
c lavale 
(hll  ale 
( la,  ale 
capilale 
c1al a le' 
capi tate 
c la' <llc 
c la\  ale 
cla, ale' 
l'dpl 1alL' 
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;:; ;:; ;:; ;:; � -; -; -; f 
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e:: C- -t :r: ;9 cr, cr 
r I 
:G 
Glossary 
A l lee effects: I n verse dens i ty-dependent effects that occur when a component of i nd i v idual  
fi t ness ( e .g .  rate of  reproduct ion ) decreases d isproport ionate ly  i n  res ponse to a decrease in 
popu l at ion  dens i t y  or s ize (A I  lee,  1 95 1 ) . 
A lways herkogamous:  where t he s t igma i i n i t i a l l y  exserted beyond t he  ant hers and rema ins 
�O.  
A u togamous self-ferti l i zat ion :  flowers t hat can se l f-po l l  i nate autonomous I y .  
Basicole:  Plants that on l y  i n habi t base rich s i tes  ( e .g.  l i mestone or magnes i tc ) .  
Brush b lossom : These flowers have a narrow corol l a  t ube.  w i t h  a ri m of conspic l lol ls  
�cL l Ics and free f lat  corol la  lobes. but  d i ffer from the  tube bl ossom type i n  hav ing  an thers and 
s t igma on long exerted fi l aments  and s ty les .  
Calcicole: Plants  that on l y  i n habi t  ca lc ium rich s i tes ( e .g .  l i mestone or marb le ) .  
Oichogamy: temporal separat ion of st ig rna and anther presenta t ion .  
Funnel blossom : These flowers have Lt w ider corol l a  t ube tha t  i s  more or less runne l  
... haped . The coro l l a  lobes are spread i ng rat her t han flat and often  fused abovc t he sca les g i v i ng  
t he  flower a funne l  shape . 
Ceitonogamy:  wit h in  p lant  pol l i nat ions .  
Herkogamy:  spat ia l  separat ion  of st i gma and an ther presentat ion .  
I n i t ia l ly  herkogamous: where t he s t igma i n i t i a l l y  protrudes but  coro l l a  ex tens ion l i fts  t he 
; l n t hers above t he s t igma dur ing  an thes is .  
Never herkogamous: where the anthers and s t igma are in c l ose contact t hroughou t .  
Precocious style: s ty le  t hat protrudes from the c losed bud prior to t he bud open ing .  
Protogyny:  t he form of d ic hogamy i n  wh ich  st igma presentat ion  precedes an ther  
presenta t ion  ( oppos ite of  protandry ) .  
Selfing  Rate:  Rate at  wh ich  p l an ts  are able to  produce seeds when pol l i nator service is  
oc luded . 
Tube b lossom : These flowers usua l l y  have a narrow coro l l a  tube of variable length .  The tube 
i s  framed by conspicuous coro l l a  scales, w i t h  fla t .  free coro l l a  l obes .  Fi lament s  a re more or less 
__ hort carry i ng  ant hers near t he top of t he tube,  but  t he degree of  i nc l us ion/exert ion  varies .  
Ul t ramafic: Rock t hat has a very h igh content of i ron  and magnes i um .  
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