Description from Flora of China
Herbs perennial, erect or ascending, rarely prostrate, almost simple or few branched at base, 12-40 cm tall; rootstock often tuberous; branches sometimes with short branchlets, strigillose. Leaves often opposite, sometimes alternate on lower or upper stems; stipules triangular, 2-6 mm; petiole 0.2-1.8 cm; leaf blade ovate or broadly ovate, lanceolate or narrowly lanceolate, usually 1.2-9 × (0.6-)0.8-3 cm, smallest ones on short branchlets, herbaceous, secondary vein 1 or 2 pairs, abaxial surface sparsely or sometimes densely strigillose or strigose along veins, adaxial surface glabrous or sparsely strigillose; base cuneate to rounded, rarely subcordate, margin entire, apex subobtuse, acuminate, or shortly so. Glomerules often bisexual, 2.5-5 mm in diam., bisexual ones in nodes of proximal leaves, female in distal axils; bracts triangular, 2-3 mm, ciliate. Male flowers: perianth lobes 4, narrowly oblong or oblong-oblanceolate, connate to middle, 1.2-1.5 mm, puberulent, apex acute or cuspidate. Female perianth tube ellipsoid or rhombic, 0.8-1 mm, 1.5-1.8 mm in fruit, puberulent, inconspicuously ca. 9-ribbed or 4-winged, apex 2-toothed. Achenes white, light to dark yellow or light brown, ovoid, 1-1.2 mm. Fl. Jul-Aug, fr. Aug-Oct.
Grasslands, thickets by streams, wet places, sunny and somewhat moist places by rice fields; 100-800(-1300) m. S Anhui, Fujian, S Gansu, Guangdong, Guangxi, Hubei, Hunan, Jiangxi, Sichuan, Taiwan, E and S Yunnan, W Zhejiang [India, Indonesia, Japan, Kashmir, Malaysia, Myanmar, Nepal, Papua New Guinea, Pakistan, Philippines, Sri Lanka, Thailand, Vietnam; Australia, Maldives, Polynesia, Yemen (Socotra); introduced in Africa and the New World].