9. Polygonum plebeium R. Brown, Prodr. 420. 1810.
铁马鞭 tie ma bian
Polygonum aviculare Linnaeus var. minutiflorum Franchet; P. changii Kitagawa; P. humifusum Pallas ex Ledebour var. mandshuricum Skvortsov; P. parviflorum Y. L. Chang & S. H. Li (1959), not Schott (1818), nor Gromov (1917); P. plebeium subsp. changii (Kitagawa) V. N. Voroschilov.
Herbs annual. Stems prostrate, 10-40 cm tall, much branched from base, usually internodes shorter than leaves. Petiole very short or nearly absent; leaf blade narrowly elliptic or oblanceolate, 5-15 × 2-4 mm, both surfaces with conspicuous midvein and inconspicuous lateral veins, base narrowly cuneate, margin entire, apex obtuse or acute; ocrea white, 2.5-3 mm, membranous, apex lacerate. Flowers 3-6, in axillary fascicles; bracts membranous. Pedicels shorter than bracts, articulate at middle. Perianth green, margin white or pinkish, 5-parted; tepals narrowly elliptic, 1-1.5 mm, abaxially with prominent veins. Stamens 5; filaments included, slightly dilated at base. Styles 3, rarely 2, very short; stigmas capitate. Achenes included in persistent perianth, black-brown, shiny, broadly ovoid, trigonous or biconvex, 1.5-2 mm, smooth. Fl. May-Aug, fr. Jun-Sep. 2n = 20.
Near fields and roads, wet areas; sea level to 2200 m. Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Xizang, Yunnan, Zhejiang [India, Indonesia, Japan, Kazakhstan, Myanmar, Nepal, Philippines, Russia (Far East), Thailand; N Africa, Australia, ?introduced in Europe].