"Usu-no-ki" (Vaccinium hirtum var. pubescens) belongs to Ericaceae (the Azalea family). It is a small deciduous tree that is endemic to Japan, and distributed to Hokkaido, Honshu, Shikoku and northern Kyushu. This tree grows in mountane to sub-alpine forest edges and rocky places, and can reach 50-100 cm in height. The leaves are ovate-elliptic to broad lanceolate and alternate with fine toothed edges. The reddish tinged, yellowish-green, bell-shaped flowers bloom in the axils from April to June. The fruits are berried and ripen red in July through September. The seeds are quinqu-angular.