Polygonum plebeium

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.

Plants bluish green, homo-phyllous. Stems prostrate, much-branched from base, not wiry, 10-40 cm, papillose-scabridulous. Leaves: ocrea 1-veined, 2.5-3 mm, proximal part cylindric, distal part laciniate; petiole 0-1 mm; blade bluish green, narrowly elliptic or oblanceolate, 5-16 × 1-4 mm, margins flat, apex obtuse or acute, papillose-scabridulous; stem leaves 1-1.5(-2) times longer than adjacent branch leaves, distal leaves overtopping flowers. Inflorescences axillary; cymes uniformly distributed, 3-6-flowered. Pedicels exserted from ocreae, 3-5 mm. Flowers closed; perianth 1-1.5 mm; tube 12-27% of perianth length; tepals overlapping, green with white or pink margins, petaloid, not keeled, elliptic, cucullate; midveins unbranched, thickened; stamens 5. Achenes enclosed in perianth, black-brown, broadly ovate, 2-3-gonous, 1.5-2 mm, faces subequal, apex not beaked, edges concave, shiny, smooth; late-season achenes common, 2-4 mm. 2n = 20.

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].

Africa, W. Asia, Himalaya, India, east to China and Ryukyu, Malaysia, Australia.

introduced; Idaho; e Africa; s Asia; Australia.

300-1400 m

Flowering May-Oct.

Near fields and roads, wet areas; sea level to 2200 m.

Disturbed sites; 50-500m.

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.