The "Ryobu" (Clethra barbinervis) belongs to Clethraceae (the Clethra family). It is a semi-tall deciduous tree that is distributed all over Japan and the Korean Peninsula. This tree grows in sunny dales and can reach 8-10 m in height. The leaves are obovate-oblong and alternate in end of twigs. The racemes are borne and bloom white flowers from June to August. The young shoots are edible after boiling and removing harshness. The Japanese name is curious, but according to Koichi Izumi, it is a corruption of "ryobi" (dragon's tail), which describes the shape of the inflorescence. "Ryobu" also means "dragon's tail," and is said to be the opposite of "oka-torano-o" (tiger's tail), a member of the primrose family. In its ancient name, it is called "Hata-tsumori," and it appears in the Manyoshu (Japan's oldest anthology of poetry). It has been planted as a garden tree because of its beautiful and elegant fall leaves.