37. Polygonum kawagoeanum Makino, Bot. Mag. (Tokyo). 28: 115. 1914.
柔茎蓼 rou jing liao
Persicaria kawagoeana (Makino) Nakai; P. tenella (Blume) H. Hara var. kawagoeana (Makino) H. Hara; Polygonum micranthum Meisner; P. minus Hudson subsp. micranthum (Meisner) Danser; P. minus subsp. procerum Danser; P. minus var. procerum (Danser) Steward; P. tenellum Blume var. micranthum (Meisner) C. Y. Wu.
Herbs annual. Stems ascending or decumbent, 20-50 cm tall, slender, usually branched from base, glabrous, rooting at lower nodes; internodes 2-3 cm. Petiole very short or nearly absent; leaf blade narrowly lanceolate, 3-6 cm × 4-8 mm, both surfaces pubescent or glabrate, appressed hispid along midvein, base usually rounded, margin shortly ciliate, apex acute; ocrea tubular, 8-10 mm, membranous, sparsely appressed hispid, apex truncate, ciliate, cilia 2-4 mm. Inflorescence terminal or axillary, spicate, erect, dense, 2-3 cm; bracts funnel-shaped, margin largely ciliate, each 2-4-flowered. Pedicel 1-1.5 mm. Perianth rose-pink, 5-parted; tepals elliptic, 1-1.5 mm. Stamens 5 or 6. Styles 2; stigmas capitate. Achenes black, shiny, ovoid, biconvex, 1-1.5 mm. Fl. May-Sep, fr. Jun-Oct.
Moist valleys, waste areas, field margins; sea level to 1700 m. Anhui, Fujian, Guangdong, Guangxi, Hainan, Jiangsu, Jiangxi, Taiwan, ?Xizang, Yunnan, Zhejiang [Bhutan, India, Indonesia, Japan, Malaysia, Nepal, Sikkim].