This BioProvince (as defined by Armen Takhtajan) consists of the Bonin and Volcano islands situated in the eastern Pacific approximately 840 km southeast of Japan. The Bonin Islands known to the Japanese as the Ogasawara Islands formed some 48 million years ago. They are mainly composed of an andesitic volcanic rock called boninite that is rich in magnesium oxide, chromium and silicon dioxide. The Volcano Islands, on the other hand, have a much younger geology. Iwo Jima, for example, is classed as a dormant volcano. Most of these islands are characterised by towering sea cliffs up to 100 m high in places. The climate is subtropical but with a distinct seasonal temperature variation and a dry season that typically occurs from January to March. In total, there are about 483 vascular plants and about 160 of these are endemic. Of the flowering plants, about 80% are endemic and there are two endemic genera (Boninia and Dendrocacalia) both of which are monotypic. Most of the native plants are of sub-tropical Asiatic origin and many of the endemics are related to eastern Asiatic taxa particularly from China and Japan. The endemics also include a small tropical element. As far as links with other Pacific islands are concerned, this BioProvince has much more in common with islands to its west such as Taiwan and the Ryukyu Islands rather than the closer Mariana Islands and other parts of Micronesia to the northwest.
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|