This area specializes in growing and displaying endangered plants from the Ogasawara and Ryukyu Islands. Both these island groups are situated at a latitude of around 27 degrees north, and are the only subtropical regions in Japan. The two island groups were formed by very different geologic processes, and as a result each supports its own unique flora.
The Ogasawaras are oceanic islands formed by uplifting of the seabed and have never been connected directly to the mainland. The plants seen on these islands today all arrived here by chance and subsequently naturalized. Later, they evolved in isolation, producing numerous endemic (found only here) species and varieties.
The Ryukyus, in contrast, were formerly connected to the Asian mainland, but were later isolated by changes in sea level due to fluctuations in climate. The plants isolated on the islands embarked on their own unique course of evolution, eventually developing into endemic species.
Both the Ryukyus and Ogaswaras are composed of small, isolated islands surrounded by the sea. In isolation they have each fostered their own unique ecosystems. The size of the habitats, as well as the number of individuals for each species, however, are limited, making the island plants and ecosystems extremely vulnerable to disruption from human activity. As a result, many of the unique plants have become extinct or are currently endangered.