Dioscorea saidae R. Knuth; D. wichurae Uline ex R. Knuth; D. yokusai Prain & Burkill.

Rhizome horizontal, irregularly branched, subcylindric, 0.7--1 cm thick; cork light brown, rough; roots borne on lower side of rhizome, fibrous. Stem twining to left, grooved, smooth. Leaves alternate, simple; petiole 5--12 cm; leaf blade drying greenish, cordate to ± triangular-cordate, (3--)5--14 × 5--10.5 cm, adaxially glabrous, abaxially sometimes papilliferous along veins, basal veins 7 or 9, base cordate with rounded sinus, margin entire or sometimes undulate to obscurely lobed, apex acuminate or caudate. Male spikes solitary or paired, often branched, lax, to 7 cm, sometimes in lax, axillary panicles. Male flowers: solitary or in cymules of 2(--4); pedicel to 1.7 mm; bract and bracteole 1; perianth saucer-shaped, 3.5--4 mm in diam., outer lobes oblong, ca. 1 mm wide, apex rounded, inner ones ca. 0.7 mm wide; stamens 6, inserted at base of perianth, filaments curved outward. Female spike solitary, rarely paired, sometimes branched. Capsule reflexed at maturity, light brown, glossy, oblong-ellipsoid, 1.8--2.2 cm, base rounded, apex emarginate to truncate; wings 0.6--0.7 cm wide. Seeds inserted near base of capsule, winged ± all round but wing much wider toward capsule apex. Fl. Jun--Aug, fr. Aug--Oct.

Mixed forests, bamboo forests, usually along ravine sides; near sea level to 1000 m. S Anhui, Fujian, Guizhou, S Henan, Hubei, Hunan, Jiangsu, S Jiangxi, S Sichuan (Yibin Shi), Zhejiang [Japan, Korea].