7. Dioscorea panthaica Prain & Burkill, J. Asiat. Soc. Bengal, Pt. 2, Nat. Hist. 73(Suppl.): 6. 1904.
黄山药 huang shan yao
Dioscorea biserialis Prain & Burkill.
Rhizome horizontal, irregularly branched, cylindric; roots sparse, fibrous. Stem twining to left, straw-colored, glabrous, smooth. Leaves alternate, simple; petiole 7--13 cm; leaf blade abaxially grayish white, drying dark brown, triangular-cordate, to 18 × 14 cm, glabrous, basal veins 7, conspicuously pale, base cordate or broadly so, margin entire or slightly undulate, apex acuminate. Male spikes solitary or 2 or 3 together, branched, to 10 cm, very slender. Male flowers: solitary or in cymules of 2 or 3, sessile; bracts boat-shaped; perianth yellowish green, funnelform, ca. 2 mm, lobes adaxially yellowish brown spotted, ovate; stamens 6, inserted at base of perianth, anthers dorsifixed. Female spike to 10 cm, few flowered. Female flowers: staminodes 6. Capsule reflexed, brownish yellow, densely purplish brown freckled, shiny, obovoid, 2.4--2.7 cm, base cuneate, apex shallowly emarginate to subtruncate; wings 0.9--1.2 cm wide. Seeds inserted near middle of capsule, winged all round. Fl. May--Jul, fr. Jul--Sep.
Scrub forests, mountain slopes; 1000--3500 m. W Guizhou, SW Hubei (Enshi Xian), NW Hunan, W Sichuan, Yunnan [Thailand].
The synonym Dioscorea biserialis has two syntypes: a fruiting specimen, Forrest 10951, which belongs to D. panthaica and a male plant, Maire s.n., which has not been seen by the present authors.