Other research has revealed the chemical basis for insect attraction to orchids and the ecological consequences of deceptive pollination. Bioassays testing orchid-pollinator specificity can define habitats and separate closely related species. An exceptionally high proportion of WA orchids have specific insect pollinators. Mycorrhizal fungi also allow efficient propagation of terrestrial orchids for reintroduction into natural habitats and for bioassays to test habitat quality.įour categories of WA orchids are defined by the following pollination strategies: (i) nectar-producing flowers with diverse pollinators, (ii) non-rewarding flowers that mimic other plants, (iii) winter-flowering orchids that attract fungus-feeding insects and (iv) sexually deceptive orchids with relatively specific pollinators. These bioassays show that mycorrhizal fungi are concentrated in coarse organic matter that may be depleted in some habitats (e.g. These fungi may be a key factor influencing the distribution of orchids and their presence can be tested by orchid seed bait bioassays. The majority of rare and common WA orchids studied have highly specific mycorrhizal associations with fungi in the Rhizoctonia alliance, but some associate with a wider diversity of fungi. These threats require science-based recovery actions resulting from collaborations between universities, government agencies and community groups.įungal identification by DNA-based methods in combination with compatibility testing by germination assays has revealed a complex picture of orchid–fungus diversity and specificity. Major threats to rare orchids in WA include habitat loss, salinity, feral animals and drought. The orchid family is highly diverse in Western Australia (WA), with over 400 recognised taxa of which 76 are Declared Rare or Priority Flora. This review summarises scientific knowledge concerning the mycorrhizal associations, pollination, demographics, genetics and evolution of Australian terrestrial orchids relevant to conservation.
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