This BioProvince (as defined by Armen Takhtajan) includes the Kerguelen Islands, Marion Island, Prince Edward Islands, Crozet Islands, Heard Islands, McDonald Island, Saint Paul Island and Amsterdam Island in the southern Indian Ocean. They are of volcanic origin and Marion and Prince Edward Islands are said to be about 500,000 years old. Data from the Meterological Station on Marion shows that they experience a cool, hyperoceanic climate with average temperatures of about 5°C that shows little seasonal or diurnal variation. However, they are almost continually battered by high winds and high levels of precipitation and are generally overcast - days with full sunshine are very rare. The flora consists of just 45 species of vascular plant of which 33 are flowering plants, 10 are ferns, including Elaphoglossum randi (endemic to Prince Edward Islands), and 2 are lycopods (Lycopodium magellanicum and L. saururus). In terms of floristic affinities, the BioProvince is close to Tierra del Fuego, despite being geographically closer to South Africa and Australia. Altogether there are some 13 endemic vascular plants, but also about 25 endemic bryophytes and some 13 endemic lichens. However, most of the indigenous vascular plants have widespread distributions in temperate regions of the southern hemisphere. It has been said that many of these remote island species may have been driven out of Tertiary Antarctica as the temperature plummeted and have since achieved circumpolar ranges through transoceanic dispersal during the Quaternary. The vegetation can have a very bleak and monotonous appearance from a distance partly due to the absence of trees, shrubs or other tall-growing plants, but on closer inspection several different vegetation types can be distinguised including Crassula maritime cliff formations, Poa cookii grasslands, Acaena magellanica wetlands, Juncus scheuchzerioides oligotrophic mires, Blechnum penna-marina swards and Azorella Fjaeldmark. However, these descriptions are mainly based on Marion and Prince Edward Islands.
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|