Dioscorea is a genus of over 600 species of flowering plants in the family Dioscoreaceae, native throughout the tropical. Dioscorea nipponica Makino, Rhizome horizontal, many branched, cylindric, more than 1.5 cm thick; cork layer persistent or readily detached. Stem twining to left, drying green or reddish brown, to 5 m, glabrescent. Leaves alternate, simple; petiole 10--20 cm; leaf blade shiny, drying yellowish green, broadly cordate to palmately unequally 3--7-lobed, very variable in shape, 7--15 × 4--13 cm, glabrous or sparsely minutely setose especially along veins, basal veins 7 or 9, outermost ones often forked, base cordate, margin undulate to prominently bluntly toothed or lobed, apex acuminate. Mixed forests, scrub forests, warm-temperature transitional areas; 100--1800 m. Anhui, Gansu, Guizhou, Hebei, Heilongjiang, Henan, Hubei, N Jiangxi, Jilin, Liaoning, Nei Mongol, Ningxia, S Qinghai, Shaanxi, Shandong, Shanxi, NW Sichuan, N Zhejiang [Japan, Korea, Russia].