18. Dioscorea birmanica Prain & Burkill, J. Asiat. Soc. Bengal, Pt. 2, Nat. Hist. 73: 185. 1904.
独龙薯蓣 du long shu yu
Rhizome horizontal, irregularly branched, bulky; cork cracked, tessellated; transverse section pink; bases of old roots becoming hard and ± thornlike. Stem twining to left, faintly grooved, glabrous, or pubescent to puberulent and glabrescent, abundantly prickly proximally, prickly only at nodes distally, smooth apically. Leaves alternate, simple; petiole 4.5--9 cm, often with recurved prickles; leaf blade ovate or broadly so, to 15 × 16 cm, glabrous or pubescent along main veins abaxially, main veins sometimes prickly, basal veins 7--11, base cordate with narrow or broad sinus and rounded auricles. Male spike produced before leaves on new stem, solitary, lax, 35--45 cm. Male flowers: in cymules to 1 cm, subsessile; bracts brown, lanceolate, ca. 1.5 mm; bracteoles absent; perianth narrowly campanulate, proximally villous, lobes erect, oblong-lanceolate, ca. 2.5 mm, apex rounded; stamens 6, inserted in throat of perianth tube, slightly shorter than perianth, filaments longer than anthers. Female spikes 20--30 cm. Female flowers: staminodes minute. Capsule reflexed, yellow-brown, oblong-obovoid, angular in outline, 2--3 cm, densely puberulent, glabrescent, base truncate to rounded, apex retuse to rounded; wings 1--1.5 cm wide. Seeds inserted near middle of capsule, winged all round.
About 400 m. NW Yunnan (Gongshan Drung-Nu Zu Zizhixian) [Myanmar, Thailand].
The present authors have not seen any Chinese material of this species.