A Guide to Dendrobium of Australia

Description:

The genus Dendrobium is one of the largest and most widespread orchid genera, with a long history associated with the discovery of Australia and its regions. In the 19th and 20th centuries the number of 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 represented in more than half of the Dendrobium sections, and about 34 species are endemic. The isolation of the island continent of Australia for around 40 million years following the breakup of Gondwanaland is a key factor in the high rate of endemism. 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