白背楼梯草 bai bei lou ti cao

Herbs perennial, monoecious, 15-35 cm tall. Stems ascending, often simple, quadrate with distinct angles, sparsely puberulent. Leaves alternate; nanophyll absent; stipules lanceolate, ca. 2 × 0.5 mm, glabrous on adaxial surface and minutely puberulent on abaxial surface; petiole 0-1 mm; leaf blade narrowly elliptic, obovate, or oblong, 1.5-5.5 × 0.5-2 cm, membranous, major basal lateral veins asymmetric, 1 basal, the other arising above base, or both absent and venation pinnate, cystoliths conspicuous, dense; base with broader half rounded, margin dentate, apex acute. Male inflorescences solitary, ca. 7 mm in diam., simple; peduncle up to 4 cm; receptacle ca. 5 mm in diam.; bracteoles cymbiform. Female inflorescences solitary, ca. 4 × 3 mm; peduncle to 1 mm or absent; receptacle oblong, 3.5 × 2 mm; bracts completely connate into an unlobed, oblong involucre; bracteoles cymbiform. Male flowers 5-merous. Achenes ovoid or ellipsoidal. Fl. Sep.

* Moist forests along streams and in ravines; at medium elevations. Taiwan.