平滑蛇根草 ping hua she gen cao

Herbs, suberect, to 80 cm tall; stems subterete to slightly compressed, drying black on upper part, puberulent or subglabrous. Leaves in subequal pairs; petiole 0.5(-1.5) cm; blade drying papery, adaxially dark green, abaxially pale green, ovate or lanceolate, ± inequilateral, 4-12 × 2-4.5 cm, glabrous on both surfaces, base cuneate, margins undulate or flat, apex acute, acuminate, or caudate; secondary veins 5 or 6 pairs; stipules caducous, not seen. Inflorescence congested-cymose, many flowered, densely ferruginous hirtellous; peduncle reduced or up to 1 cm; axes reduced to shortly helicoid; bracts absent or minute. Flowers reportedly distylous, subsessile. Calyx glabrescent; hypanthium obovoid, ca. 2 mm, 5-ribbed; lobes narrowly lanceolate, ca. 1 mm, with 1 gland in each sinus. Corolla pink, subtubular, glabrous outside; tube ca. 13 mm, sparsely white villous above middle inside; lobes subovate, 1.8-2 mm, dorsally with short horn 0.1-0.2 mm, apex rostrate. Capsules not seen. Fl. Apr.

● Semi-evergreen forests; 800-1000 m. Xizang (Mêdog).

The protologue reported this species as distylous but described only one floral form, similar to the short-styled flowers of distylous species; this was described as having the stigmas positioned not far below the middle of the corolla tube and the anthers exserted.