Description from Flora of China
Polygonum caudatum Samuelsson in Handel-Mazzetti, Symb. Sin. 7: 185. 1929.
Herbs annual. Stems 30-50 cm tall, branched at base; branches decumbent or ascending, slender, striate, internodes 1.5-3 cm, upper internodes ca. 8 cm. Petiole 0.8-1.2 cm; leaf blade triangular-sagittate or narrowly sagittate, 1-3 cm × 4-10 mm, both surfaces glabrous, midvein slightly prominent abaxially, basal lobes lanceolate, apex acute; ocrea yellow-brown, 4-5 mm, membranous, oblique, apex acute. Inflorescence terminal or axillary, racemose, very lax, interrupted, 3-6 cm, several racemes aggregated and panicle-like; bracts yellow-brown, 2-2.5 mm, membranous, oblique, apex acuminate, each 2- or 3-flowered. Pedicel 3-4 mm, slender, apex articulate. Perianth white or pinkish; tepals elliptic, ca. 1.5 mm, apex rounded, accrescent. Anthers elliptic. Stigmas capitate. Achenes exceeding persistent perianth, slightly shiny, broadly ovoid, trigonous, 3-4 mm. Fl. Jun-Oct, fr. Jul-Nov.
* Valleys, mountain slopes; 1000-2200 m. S Gansu, Sichuan, Yunnan.