Australian Dendrobium species exhibit a myriad of plant forms and flower presentations, with subtle or brilliant colours. Many flowers are fragrant and last from less than a day to several weeks. The genus Dendrobium, contains nearly 1600 species worldwide, with a long history associated with the discovery of Australia and its regions.
In the 19th and 20th centuries the number of Dendrobium species increased steadily, with a few recent discoveries of variants, but no entirely new species has been described in Australia for twenty years. There are about 60 species in Australia compared to approximately 560 species in neighbouring New Guinea. Australian dendrobiums are diverse with more than half of the Dendrobium sections being represented with at least one example. With the breakup of Gondwanaland, some 40 million years ago, the resulting isolation of Australia as an island continent has been a key factor in there being a total of 34 species being endemic.
Distribution in Australia is restricted to specific habitats along the eastern coastline associated with the Great Dividing Range, and a small number of species extend west to the northern parts of Queensland, the Northern Territory and Western Australia. The remaining areas are too hot and dry to sustain the mainly epiphytic and lithophytic Dendrobium habit. A small number of species are terrestrial or semi-terrestrial in the wetter areas of north Queensland. With the exception of Dendrobium cunninghamii in New Zealand, Australia has the most southerly occurring dendrobiums. They have adapted to a wide range of temperatures, from warm tropical to cold, and to very variable rainfall, including long periods of drought.
The largest populations and diversity are found in the subtropical and tropical rainforests of New South Wales and Queensland. Some of the most localised and rarest species occur on the northern Cape York Peninsula and are either endemic, or a southern extension of a distribution range in New Guinea and Asia. A small number of species are found in the islands of the Western Pacific, notably New Caledonia and Lord Howe Island. All Australian species and their main variants, a total of around 80 taxa, are included in this volume.
