Included in this BioProvince (as defined by Armen Takhtajan) is the Ryukyu Archipelago situated between Kyushu and Taiwan, and comprising Okinawa, Ishigaki, Iriomote, Tokuno-Shima, and the Amami and Tokara islands. There are more than 60 islands the largest of which is Okinawa. They appear to be composed of Tertiary sandstone of ‘continental’ origin and are thought to have formed some 1.7-5 million years ago when they became separated from the Asian mainland as a result of rising sea levels. They experience a sub-tropical climate with high rainfall and the Kuro Shyo Current keeps the climate very mild. Like Taiwan the flora is transitional between Holarctic and Palaeotropical floras. Also present are ancient Japanese elements such as Aucuba (Aucuba japonica) and Heloniopsis (Heloniopsis kawanoishow) that were broadly distributed during the Middle Tertiary Period when Japan and the Ryukyu Islands formed part of the edge of the Asiatic continent. The largest number of vascular plant species (142) is found on Amami-Oshima, which is probably the second largest island after Okinawa. Endemism is comparatively low with just one endemic genus (the palm Satakentia) represented by Satakentia liukiuensis, which is found on Iriomote Island, and at least 23 endemic species made up of both Holarctic and tropical elements. These including Acer itoanum, Adinandra ryukyuensis, Aster miyagii, Cardiandra amamioshimensis, Chikusichloa brachyanthera, Geotaenium gelasinum, Heterotropa fudsinoi, Hydrangea scandens subsp. liukiuensis, Ilex dimorphophylla, Oxalis amamiana, Pinus luchuensis, Rhamnus kanagusuki, Schima wallichii subsp. liukiuensis, Vaccinium amamianum, Viburnum tashiroi, Viola amamiana and Zanthoxylum amamiense.
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|