68. Polygonum microcephalum D. Don, Prodr. Fl. Nepal. 72. 1825.
小头蓼 xiao tou liao
Herbs perennial. Rhizomes stout. Stems erect or decumbent, 40-60 cm tall, angulate, branched. Petiole 1-1.2 cm, winged; leaf blade broadly ovate or triangular-ovate, 6-10 × 2-4 cm, both surfaces glabrous or pilose, base subrounded, decurrent along petiole forming a wing, margin entire, ciliate, apex acuminate; ocrea tubular, lax, 7-10 mm, pubescent, apex truncate, ciliate. Inflorescence terminal, usually geminate, capitate, 5-7 mm in diam.; peduncle glabrous or glandular hairy; bracts ovate, apex acute. Perianth white or pinkish, 5-parted; tepals elliptic, 2-3 mm. Stamens 8, included. Styles 3, connate to below middle; stigmas capitate. Achenes black-brown, opaque, broadly ovoid, trigonous, 2-2.5 mm, punctate.
Forests, grassy places; 500-3200 m. S Gansu, Guizhou, Hubei, Hunan, S Shaanxi, Sichuan, Xizang, Yunnan [Bhutan, India, Nepal, Sikkim].