Centre for Australian National Biodiversity Research
David L. Jones, Tara Hopley, Siobhan Duffy, Karina Richards, Mark Clements
Reproduced from ABRS Biolog No.30 October 2005
Orchids are among the most highly evolved and specialised groups in the Plant Kingdom. Their flowers exhibit a truly amazing array of colours and forms ranging from reduced and basic structures to complex adaptations verging on the bizarre. With estimates ranging as high as 25 000–35 000 species in more than 800 genera, orchids are obviously a significant component of the world’s flora. In Australia we have some 1200–1400 species of orchids in 192 genera, including many groups with unique features and remarkable specialisations.
The diversity of Australian orchids includes the endemic genus Rhizanthella, members of which complete their entire life cycle underground. Other genera have an actively motile labellum system capable of being triggered by the lightest touch and rapidly snapping shut to trap an insect visitor, resetting itself after short periods of time. Numerous orchid species mimic wingless female wasps so accurately that they deceive the male wasps into attempting to mate with the flowers and so assisting pollination (a phenomenon known as pseudocopulation).
Australian native orchids have been the subject of detailed studies by members of the orchid research group at the Centre for Plant Biodiversity Research (CPBR) in Canberra. This research has involved aspects of orchid biology, morphology and conservation. It has resulted in the recognition and formal description of more than 350 new taxa and the erection of some 43 new genera by this research group. Now, with the support of ABRS, much of the information gathered by this group over the last fifteen years will be made available to the public in the form of a computer-based interactive identification key, to be known as the Interactive Key to Australian Orchid Genera.
Traditionally orchid taxonomy has relied heavily on floral morphology: some research groups concentrate solely on aspects of particular organs such as the column. Modern techniques involve a broad-based approach using biological aspects and habitat preferences as well as vegetative and floral morphology. The relatively recent technique of isolating gene sequences from chloroplast and nuclear DNA has provided extra data useful for comparative studies and simplified the formation of detailed phylogenies. Interestingly, many of these studies, including those carried out at the CPBR, highlight the importance of vegetative morphology within various orchid groups and draw attention to the conservative nature of many aspects of floral morphology. Molecular sequence studies such as these, when combined with detailed morphological studies, have resulted in significant and challenging changes in the interpretation of Australian orchid genera. In some cases these changes have proved to be controversial and have not been widely accepted in the botanical community. New concepts derived from this detailed research are adopted in this key, with explanations about the research data and the reasoning behind the changes.
Orchids are considered the most highly evolved group within the monocotyledons, surviving only with the aid of specific symbiotic fungal relationships and through intricate associations with various groups of insects and birds to achieve pollination. As a group they have a devout following of admirers, amateurs and professionals, who devote themselves to all aspects of orchid taxonomy, evolution, horticulture and conservation. Consider the significance of orchids as horticultural subjects: more than 150 orchid societies are currently listed in Australia and an estimated 100 000 man-made orchid hybrids are registered in various countries throughout the world.
The Interactive Key to Australian Orchid Genera is a simple computer-based system using Lucid™ software for accurately identifying Australian native orchids to generic rank. Genera have been coded for 144 characters and 628 character states. These attributes mainly cover vegetative and floral features but also include characters for habitat preferences and major geographic regions of distribution. An abbreviated character set (Quickset) of 30 characters and 143 character states is also available as a tool for rapid and efficient identification. This character set was developed following feedback from people who tested early versions of the key; it will be regularly refined. Descriptive notes, colour photographs and/or diagnostic line drawings aid the interpretation of characters and character states.
Linked fact sheets summarise taxonomic, descriptive, biological, ecological and distribution information for each genus. They include a detailed botanical description of the genus; emphasis on significant generic features including a simplified version of the generic characters; nomenclatural and taxonomic notes; synonyms; common names; habitat; biogeographical, biological and ecological information. Detailed distribution maps and an extensive bibliography and reference list are also included. A comprehensive Catalogue of Australian Orchid Names, including synonyms at the species level, provides a cross-reference for the many new changes in nomenclature and taxonomy in Australian orchids.
The key is fully illustrated throughout with representatives of the range of species within each genus. Each genus is complemented by numerous colour photographs chosen to show the range of variation commonly encountered. Detailed line drawings, including enlarged floral parts, are provided for many of the genera. Some annotated scanning electron micrograph images of floral structures are also included.
This interactive key brings together many aspects of the most comprehensive and detailed study yet undertaken on the Australian Orchidaceae. It includes results that sometimes confirm taxonomic thought, and at other times are at odds with traditional views on the generic limitations within the family but which are in line with complementary research into other groups overseas.
The Interactive Key to Australian Orchid Genera does not provide the last word on the subject of the classification of Australian orchid genera but hopefully it will encourage more students to take up studies into these fascinating plants.
The Interactive Key to Australian Orchid Genera is expected to go to press in December 2005.