Fig. 1.

Map showing the distribution sites of the plant species used in this study a, and enlarged map of the Ogasawara Islands, where the six endangered plant species in this study are distributing b. Pictures boxed in red show the endangered island endemic (EIE) species with its classification in the Red List category (bottom left), and pictures boxed in white show the non-endangered (NE) species in each genus. Each painted island map on the right side of the picture of endangered species indicates its distribution; black-painted means distributing in the island, gray-painted means extinct in the island, and white-painted means not-distributing in the island. The number below the painted island map indicates the estimated current number of individuals of the endangered species. The Red List category is as follows; CR is Critically Endangered, EN is Endangered, and VU is Vulnerable. Distribution ranges of the non-endangered species are as follows; A. pygmaea in Kyushu and the Ryukyu Archipelago, A shikotanensis in Honshu, C. lanceolatam in Honshu, Korean Peninsula and Mainland China, C. keiskeanum in Honshu, Shikoku, Kyushu, Korean Peninsula and Mainland China, C. triplicata in Kyushu, the Ryukyu Archipelago, Taiwan, and Mainland China, and M. candidum the Ryukyu Archipelago, Taiwan, and Mainland China