6. Dioscorea deltoidea Wallich ex Grisebach in Martius, Fl. Bras. 3(1): 43. 1842.
三角叶薯蓣 san jiao ye shu yu
Rhizome horizontal, ginger-shaped, 1.2--1.5 cm thick. Stem twining to left, drying light brown to purplish brown, grooved. Leaves alternate, simple; petiole 4--10(--15) cm; leaf blade drying gray-green, triangular or triangular-ovate, usually 3-lobed, 5--9 × 4--5.5 cm, adaxially glabrous, abaxially papillose-setulose along veins, basal veins 3--7, outermost ones much shorter, base shallowly cordate (with very broad sinus) to subtruncate, apex of middle lobe acuminate, apex of lateral lobes rounded. Male spike solitary, sometimes branched, 9--16 cm. Male flowers: solitary or paired, sessile; bracts broadly ovate, membranous, apex acute; perianth saucer-shaped, 3--3.5 mm in diam., lobes ovate, ca. 0.8 mm wide; stamens 6, inserted at base of perianth, anthers 3 introrse and 3 extrorse, connectives not fork-shaped. Female spike to 5 cm, 4--6-flowered. Female flowers: staminodes present. Capsule reflexed, brown at maturity, purplish brown spotted, globose or oblong-obovoid, (1.5--)1.8--2.2 cm, base rounded, apex emarginate or rounded; wings (0.7--)1.2--1.4 cm wide. Seeds inserted near middle of capsule, ovate, winged all round. Fl. May--Jun, fr. Jun--Sep.
Broad-leaved forests, scrub forests; 2000--3100 m. Sichuan, Xizang, Yunnan [Bhutan, India, Myanmar, Nepal, Sikkim, Thailand, Vietnam].
Dioscorea deltoidea var. orbiculata Prain & Burkill (Ann. Roy. Bot. Gard. (Calcutta) 14: 25. 1936) was published for a Chinese collection with the capsule ± globose. However, the description lacked a Latin diagnosis so the name is invalid. Chinese material often differs from typical, Indian material by the distinctly 3-lobed leaves, but the separation is not very clear-cut and more detailed investigations should be undertaken to clarify the status of these plants.