Southwest Australian BioProvince
This comparatively small BioProvince (as defined by Armen Takhtajan) comprises the exteme southwestern part of Australia including the Darling and Sterling Ranges and the coastal plain from the Edel Peninsula in the north to roughly Point Culver between the cites of Esperance and Eyre. The geology is complex and varied but appears to have had a long dynamic Precambrian history of crustal fragmentation and aggregation through continental collision and accretion. Much of the area experiences a Mediterranean climate but away from the coast this rapidly gives way to the arid and hot desert conditions of central Australia. The flora includes some 5469 species of vascular plants, 4331 (about 79%) are endemic, and of the 685 genera, a massive 73 are endemic making this one of the most distinctive biozones on the planet. However, only one plant family (Cephalotaceae) seems to be completely endemic to this zone but there are a further 4 families endemic to Australia.
The species represented by the endemic genus Nuytsi (Nuytsia floribunda), known locally as the Christmas tree, is of some interest in being the only arborescent member of the 500 or so species of Loranthaceae (the mistletoe family) worldwide. All of the others are either ground dwelling shrubs or parasites living in the branches of host trees. The Christmas tree is a semi-parasite that derives much of its nourishment through modified roots that penetrate the roots of other species, and these can include a variety of unrelated species such as umbilifers, grasses, shrubs and trees. However, the Christmas tree’s vivid tangerine-coloured flowers make it one of the most spectacular flowering trees in the world.
The following accounts for this BioProvince have been written or will be written with particular reference to endemic and locally important species. Accounts available are displayed in green or yellow. Those displayed in red are either in the pipeline or awaiting expert contributions.
|Endemic Vascular Plant Flora|
Impatiens sodenii (Balsaminaceae) endemic to exposed rocky hills in southwestern and western Australia (Copyright © 2010 Peter Martin Rhind).