We investigated the phylogeography of the New Zealand endemic monotypic coastal tree Entelea arborescens (whau; Malvaceae). The distribution of whau in the southern North Island and South Island has been suggested to result from pre-European Māori cultivation. Whau wood is extremely buoyant and was used to make fishing floats and rafts. We sequenced two chloroplast loci and the nuclear ITS region and genotyped nine microsatellite loci from samples collected across the species’ range. The different genetic markers produced concordant results and revealed two principal genetic clusters, which were estimated to have diverged during the Pleistocene. The distribution of these clusters shows an east–west split across the northern North Island, which does not correspond to the phylogeographic patterns observed to date for other New Zealand coastal plant species and is difficult to reconcile with any known geological or environmental events. Both clusters were represented in the putative translocated populations indicating that these southern populations had multiple origins. However, the wide distribution of these genetic clusters prevents determination of the source of these southern populations and a natural origin cannot be excluded.

Clarity in species delimitation is fundamental for successfully testing evolutionary theory and is integral to implementing conservation strategies. The Old World Spiranthes sinensis species complex (Orchidaceae) has been a source of systematic confusion due to its expansive distribution and morphological variation, lacking a comprehensive systematic review. Working under an integrative phylogenetic species concept, we provide an expansive molecular phylogenetic sampling of the S. sinensis species complex, compliment this with phenological and morphological studies and clarify species boundaries in this challenging group. Our data support a re-circumscription of the S. sinensis species complex, recognizing six distinct species and one natural hybrid, with other taxa reduced to synonyms: S. australis, S. flexuosa, S. maokensis sp. nov., S. sinensis s. s., S. suishaensis, S. sunii and S. xhongkongensis (pro species, S. flexuosa x S. sinensis s. s.). The recognition of S. flexuosa also refines the distribution of S. spiralis. Our research indicates phenological divergence, reinforced by glacial vicariance, may have strongly influenced the evolution and speciation of this clade, with few observable or measurably significant morphological differences among these species (other than pubescence). We also discuss the importance and prevalence of autogamy among island populations of Spiranthes. Our work can be used by researchers working on the systematics and biogeography of other Asian and Australasian species complexes, and we underscore the continued importance of nomenclatural and specimen review and correct species identification in evolutionary and ethnobotanical studies.

The New Zealand ladies' tresses Spiranthes novae-zelandiae is a terrestrial orchid currently classified as Threatened - Nationally Vulnerable. Although considered endemic to New Zealand, morphological similarity with the widespread Eurasian Spiranthes sinensis has cast doubt on its taxonomic and biogeographic status. Habitat destruction is the main threat to the survival of S.novae-zelandiae. Unfortunately, lack of information regarding its symbiotic fungal associates and technical expertise within New Zealand with symbiotic seed germination techniques have hindered its propagation from seed. In this study we examined the phylogenetic affinities of S.novae-zelandiae using nuclear (internal transcribed spacer) and chloroplast (trnL, trnS-G and matK) DNA sequences. We also explored the diversity of fungal symbionts associated with S.novae-zelandiae and identified the fungal symbiont that promotes seed germination and seedling development using DNA sequences and in vitro seed germination experiments. Bayesian Inference analyses showed that S.novae-zelandiae is nested within S.sinensis along with Spiranthes australis and Spiranthes aff. novae-zelandiae (CHR 518297; Motutangi), a morphological variant of uncertain taxonomic status from northern New Zealand. These results support earlier suggestions that a broader concept of S.sinensis is needed to include S.novae-zelandiae and many other taxa segregated from S.sinensis. Nine fungal Operational Taxonomic Units were isolated from the roots of S.novae-zelandiae but only one promoted seed germination and seedling development. DNA sequence analyses confirmed that this isolate was a strain of Tulasnella (anamorph: Epulorhiza); a widespread mycorrhizal fungus previously found in S.australis and S.sinensis. Lastly, we describe the germination process and the steps we followed to obtain flowering plants after 2 years of seed inoculation.

Five new species of Corybas endemic to New Zealand, C. confusus , C. obscurus , C. sanctigeorgianus , C. vitreus , and C. wallii are described. These species are segregated from the Corybas trilobus aggregate based on morphometric and DNA fingerprinting (AFLP) analyses. A key to the new species is also provided, and their distribution and conservation status are included. Phylogenetic results showed that, despite the great morphological and ecological diversity of these orchids, genetic divergence between species is low, suggesting recent diversification. We also found evidence for multiple dispersal events from New Zealand to several offshore and sub-Antarctic islands.

Nearly 40% of New Zealand (NZ) orchid species are of conservation concern, some critically endangered, largely due to habitat loss. In NZ, there are currently no propagation programs for terrestrial orchids all of which rely on symbiotic fungi to provide the nutrients required for germination, and little is known about the specific fungal species that might make this possible. To develop an understanding of the fungal interactions affecting recruitment in the field, a survey of endophytic fungal diversity from the roots of Chiloglottis valida, Microtis unifolia, Pterostylis banksii, Spiranthes novae-zelandiae and Thelymitra longifolia was carried out. The identification of fungi was assisted by obtaining sequences of the ITS rDNA gene marker. Seeds of M. unifolia, P. banksii, S. novae-zelandiae and T. longifolia were inoculated with cultured endophytes that were recovered from the roots of conspecific orchids, and their effect on seed germination evaluated. Seed viability using fluorescein diacetate was assayed on all species prior to all experiments and showed moderate to high viability scores for all species. Recovered endophytes belonged to the phyla Ascomycota, Basidiomycota, and Zygomycota. The effect of the different endophytes on seed germination was variable, with five inoculants exhibiting a positive response. Three inoculants had a consistent negative effect on seed germination. The distribution of orchid symbiotic mycorrhizae in situ was investigated at Otari-Wilton’s Bush, Wellington, NZ. Mesh seed packets containing seed of M. unifolia and T. longifolia were interred for 150 days, along transects (≤ 1 metre) that originated at adult orchids at three sites, and an additional site with no adult orchids was used as a control. No small-scale patterns were detected; however, germination rates were higher at undisturbed sites. Seed viability was considerably reduced to <2% after five months under the soil suggesting M. unifolia and T. longifolia seeds do not persist in the seed bank beyond one growing season. Sequences of ITS rDNA indicate Tulasnella calospora assists in the germination of M. unifolia at this site. Similarly, Tulasnella calospora promoted germination of the Nationally Vulnerable wetland species S. novae-zelandiae. Pelotons were isolated from the roots of S. novae-zelandiae plants from a wild population from the lower north island and cultured in Petri dishes. Germination of this orchid began after 30 days from inoculation when the pelotons are already observed inside the embryo. Chlorophyllus tissue was observed after c. 80 days of inoculation. The phylogenetic relationship of Asian-Pacific Spiranthes species with New Zealand Spiranthes was also investigated using nuclear (ITS) and chloroplast (trnL-trnF) DNA sequences. Phylogenetic analyses supported the recognition of Spiranthes novae-zelandiae ‘Motutangi’ as a distinct taxonomic unit. It was also found that the Asian-Pacific Spiranthes species are in need of taxonomic revision. Methods used and developed in this thesis study could be used to identify potential orchid symbionts and pathogens, assess suitable potential relocation sites, and propagation of NZ orchids using symbiotic fungi for restoration and conservation purposes.