Persicaria barbata (Linnaeus) H. Hara; P. omerostroma (Ohki) Sasaki; Polygonum kotoshoense Ohki; P. omerostromum Ohki.

Herbs perennial, rhizomatous. Stems erect, 40-90 cm tall, robust, pubescent, simple or branched above. Petiole 5-8 mm, densely hispidulous; leaf blade lanceolate or elliptic-lanceolate, 7-15 × 1.5-4 cm, both surfaces pubescent, base cuneate, margin ciliate, apex acuminate; ocrea tubular, 1.5-2 cm, membranous, densely hispidulous, apex truncate, cilia 1.5-2 cm. Inflorescence terminal, spicate, erect, 4-8 cm, several spikes aggregated and panicle-like, rarely solitary; bracts funnel-shaped, glabrous, margin ciliate, each 3-5-flowered. Pedicel short. Perianth white or greenish, 5-parted; tepals elliptic, 1.5-2 mm. Stamens 5-8, included. Styles 3; stigmas capitate. Achenes included in persistent perianth, black, shiny, ovoid, trigonous, 1.5-2 mm. Fl. Aug-Sep, fr. Sep-Oct. 2n = 60.

Streamsides, wet areas, water sides; sea level to 1300 m. Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hubei, Hunan, Jiangxi, Sichuan, Taiwan, Yunnan [Bhutan, India, Indonesia, Malaysia, Myanmar, Nepal, New Guinea, Philippines, Sikkim, Sri Lanka, Thailand, Vietnam].