Species in the genus Dioscorea:

Dioscorea bulbifera / Nigakashuu
Dioscorea japonica / Yamanoimo
Dioscorea quinqueloba / Kaededokoro
Dioscorea tokoro / Onidokoro
　

Dioscorea bulbifera / Nigakashuu ニガカシュウ

Dioscorea bulbifera is a vine perennial found in fields and mountains, with significant oblate tuberous roots and black coverings. Leaves are of alternate phyllotaxis, 5-13cm in length and width, concentric-shaped, with tips, abruptly pointed, hairless on upper and lower surfaces, and no serrations on margins. Petioles measure 3-9.5cm long, with bulbils at axils. Dioecious: Both male and female inflorescences hang down, and those flowers are purple-tinged yellow-green; perianth lobes are 6, lanceolate-shaped, and not open flat. The fruit (capsule) is 1.5-2.5cm long, 1-1.5 cm wide, oblong shape, and has three wings. Bloom time: August-September.