与那国島植物新知見

概要

論文の詳細を見る
Yonaguni-jima, the southernmost island of the Ryukyu lslands, is situated between Iriomote-jima and Formosa. Compared with those of neighbouring islands, lriomote-jima and lshigaki-shima, the flora of Yonaguni-jima is rather poor in endemism. Only two species, Elatostema yonakuniense and Aster Walkeri are known to be endemic to this island. This paper deals with plants of taxonomic or phytogeographical interest based on collections recently made by the present authors and materials collected by various investigators. Two new forms of Limonium Wrightii are described. Three plants belonging to Asplenium, Ligustrum and Tylophora are mentioned to be noteworthy. The occurrences of Angiopteris palmifolia and Selaginella leptophylla are confirmed. Rubus fraxinifolia, Gymnema alternifolia and Angiopteris lygodiifolia are considered to be elimnated from the flora of this island. Extinction of Potamogeton pectinatus due to destruction of the habitat is reported. Some plants found on Yonaguni-jima are also present in Kashoto (Green Island), Kotosho (Bote1 Tobago or Orchid Island) and Batan Island, but are absent from the mainland of Formosa. This unique pattern of distribution is briefly discussed in this paper from a phytogeographical view point. Among plants showing this type of distribution, two plant groups are recognized. The first group contains warm temperate elements commonly distributed in the Ryukyu Islands and the mainland of Japan. The other group includes locally differenciated plants belonging to genera widespread in tropical region. Most plants belonging to the firt group show the disperasl by bird, while those belonging to the scond group by wind. Sea current can not be regarded to play any role in the dispersal of these plants. The fact mentioned here seems to indicate the presence of an established route of plant migration through these islands.

与那国島植物新知見

スポンサーリンク

概要

論文 | ランダム

スポンサーリンク