Description from Flora of China
Persicaria assamica (Meissn.) Soják.
Herbs annual. Stems ascending or decumbent, 15-30 cm tall, glabrous. Petiole 3-6 mm, sparsely appressed hispidulous; leaf blade green, blue-green when dry, elliptic-ovate or broadly lanceolate, 2.5-6 × 1-2 cm, abaxially appressed hispidulous along veins, adaxially glabrous, base broadly cuneate, apex acute; ocrea tubular, membranous, sparsely appressed hispidulous along veins, apex truncate, long ciliate. Inflorescence terminal, spicate, solitary or several aggregated and panicle-like; spike lax, 2.5-4 cm, usually decurrent at base; bracts green, herbaceous, ciliate, each 1-3-flowered. Perianth reddish, 5-parted; tepals elliptic, 2.5-3 mm. Stamens 5 or 6, included. Styles 2; stigmas capitate. Achenes included in persistent perianth, narrowly ovoid, biconvex, ca. 2.5 mm. Fl. Jun-Jul, fr. Aug-Sep.
Stream banks, wet valleys; 200-1000 m. Guangxi, Guizhou, Sichuan, Yunnan [N India, Myanmar].