2001, David Menzies, Field Trip To Study Orchids, South West Australia

An Orchid fieldtrip in South-Western Australia

by David Menzies

The First International Orchid Conservation Conference was held in Perth, capital of Western Australia from September 24th to 28th, 2001, and was attended by 130 delegates from 22 countries. At the end of a most enjoyable and informative Congress, 46 of us embarked on a five-day study tour of the south-western region of the state, where around 80% of the more than 300 terrestrial orchid species are endemic. The climate is broadly Mediterranean, having cool, wet winters and hot, dry summers. Orchids are found in a wide variety of habitats, with some species being common to many areas whereas others are very specific and local in their distribution. All have evolved in close association with their insect pollinators, resulting in some truly bizarre forms, and also stunning colours seen nowhere else in the family.

Andrew Brown, our guide, is a noted orchid botanist, and during our five days together, his good humour never left him, despite the provocation of independentminded enthusiasts who tended to disappear over the horizon at every stop. He was ably assisted by Laurie, our coach driver, a font of local information, expert navigator and provider of sustaining refreshments throughout each day. A number of orchid species require fire to encourage flowering, while others prefer to grow in seasonally wet soils. As a result, clothing tended to become both black and wet, soon forgotten in the excitement of the chase.

The most common genus is Caladenia, spider orchids to Australians, of which more than 140 species occur in the State. The common name refers to the attenuated sepals and petals of many species, the largest flowers of which are nearly 30cm long. Caladeniahave hairy stems and a single, hairy leaf, prefer open areas, and vary in flower colour from white to yellow, green or pink. A species we found every day, was C. flava, with broader, bright yellow blooms, sometimes in large numbers. After a while it became a relief to find other genera, such as: Elythranthera brunonis, the glossy, purple enamel orchid; species of the tall leek orchids, Prasophyllum; Pyrorchis nigrans, red beaks; Pterostylis recurva, the jug orchid; and various species of sun orchids, Thelymitra, which open only when it is warm and sunny. The best Thelymitrahave clear blue flowers, rare in orchids, but the nicest example was adjacent to a very dead kangaroo, which made photography almost unbearable. The most bizarre orchids are undoubtedly the hammer orchids, Drakaea sp., and the flying duck orchid, Paracaleana nigricans. Both of these diminutive charmers were found growing in open, sandy places and are examples of plants which use pseudo-copulation to encourage pollination.

Of course orchids are only a part of the rich flora, and we enjoyed seeing many of the other elements, including carnivorous plants, especially Drosera sp. in many forms, Utriculariain wet places, and, during the third day, the Albany pitcher plant, Cephalotus follicularis. Colourful legumes were very common in some areas, as well as the unique grass trees, Xanthorrhoea sp. In all, we saw nearly 80 species of orchid, and the 30 photographers among us took almost 11,000 photographs. I am most grateful to the Kew Guild for making this field work possible.

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