There is a report dating back to 1907 concerning the distribution of plants in the Ogasawara Islands. According to the report, palms, bananas, and pineapples were fruit-bearing plants, with tropical plants such as screw pines (Pandanus boninensis) and Chinese fan palms (Livistona chinensis), being seen everywhere across the islands. The report also noted the existence of Asian beach jackbean (Canavalia lineata), seaside morning glory (Ipomoea pes-caprae), beach vitex (Vitex rotundifolia), and pennywort (Centella asiatica). (Ref. 1)  

Today, many of the species on the islands are of subtropical origin, such as munin himetsubaki (Schima mertensiana), yellow boxwood (Planchonella obovata), shima horutonoki (Elaeocarpus photiniaefolius), and sharinbai (Rhaphiolepis indica var. umbellate), with almost 70% of all plant life being Southeast Asian in origin. In addition, plants of diverse origins have also become established, including those of Japanese mainland origin, such as nagabakibushi (Stachyurus macrocarpus), and those of Oceanian origin, such as arrack tree (Clinostigma savoryanum). Given that species of diverse origins have undergone unique speciation, the result is a high number of species per unit area and a high rate of endemic species. Each island is characterized by its own unique flora, and even Chichijima and Hahajima, which are only 40 km apart, each have their own endemic species. (Ref. 2, 3)

Dry shrubland of five to eight meters in height can be seen on the gentle slopes around the summits of Chichijima and Anijima, including shimaisunoki (Distylium lepidotum) and rose wood (Schima mertensiana), which are particularly suited to a dry climate. In the cloud forest zone of Sekimon on Hahajima, mesic forest up to 20 meters in height can be found, including shima horutonoki (Elaeocarpus photiniaefolius) and udonoki (Pisonia umbellifera), and mokutachibana (Ardisia sieboldii Miq.). (Ref. 2, 3)

 

Ref. 1: Hattori Hirotaro, “The distribution of plants in the Bonin Islands,” Journal of Geography, vol. 19 (1907), pp. 569-578

Ref. 2: Government of Japan, Nomination of the Ogasawara Islands for Inscription on the World Heritage List, 2010, pp. 37-51.

Ref. 3: Tokyo Metropolitan Ogasawara Branch Office, Kannai Gaiyo (Overview of the Jurisdiction), 2019 ed., p.41.