Distribution
Albania (introduced), Algeria (introduced), Angola (introduced), Austria (introduced), Bahamas (introduced), Bangladesh (introduced), Belarus (introduced), Belgium (introduced), Benin (introduced), Bulgaria (introduced), Cameroon (introduced), Cape Verde (introduced), Colombia (introduced), Congo (introduced), Cuba (introduced), Denmark (introduced), Egypt (introduced), Ethiopia (introduced), Finland (introduced), France (introduced), French Guiana (introduced), Gabon (introduced), Georgia (introduced), Germany (introduced), Greece (introduced), Guyana (introduced), Hungary (introduced), India (introduced), Iran (introduced), Italy (introduced), Ivory Coast (introduced), Japan (introduced), Kazakhstan (introduced), Kenya (introduced), Laos (introduced), Liberia (introduced), Malawi (introduced), Mauritania (introduced), Mauritius (introduced), Morocco (introduced), Mozambique (introduced), Nepal (introduced), Netherlands (introduced), Nigeria (introduced), Philippines (introduced), Poland (introduced), Portugal (introduced), Puerto Rico (introduced), Reunion (introduced), Romania (introduced), Rwanda (introduced), Saudi Arabia (introduced), Spain (introduced), Sri Lanka (introduced), Sudan (introduced), Suriname (introduced), Sweden (introduced), Switzerland (introduced), Taiwan (introduced), Tanzania (introduced), Thailand (introduced), Tonga (introduced), Tunisia (introduced), Turkey (introduced), Turkmenistan (introduced), Uganda (introduced), Ukraine (introduced), Uzbekistan (introduced), Vanuatu (introduced), Venezuela (introduced), Vietnam (introduced), Yemen (introduced), Zambia (introduced), Zimbabwe (introduced)

Plants annual, glabrous. Stems ascending to prostrate, sometimes erect, simple or branched, sometimes radiating from base and forming mats, 0.1-0.6 m. Leaves: petiole usually equaling to 2 times as long as blade; blade ovate or obovate, 1-6 × 0.5-4 cm, base tapering or cuneate, margins entire, plane, apex distinctly emarginate to almost bilobate, mucronate. Inflorescences slender terminal spikes or panicles and also axillary clusters, in some forms only axillary clusters are present; spikes erect or sometimes reflexed, green , leafless at least distally. Bracts of pistillate flowers lanceolate, inconspicuous, 0.5 mm, shorter than tepals. Pistillate flowers: tepals 3, elliptic or spatulate, not clawed, equal or subequal, 0.8-1.5 mm, margins entire, apex broadly acute; style branches erect; stigmas 3. Staminate flowers clustered at tips of spikes; tepals 3; stamens 3. Utricles compressed, subglobose to obovate, 1.2-2.5(-3) mm, exceeding tepals, smooth or faintly rugose, indehiscent. Seeds black or dark reddish brown, subglobose or broadly lenticular, (0.8-)1-1.8 mm diam., smooth, shiny, filling fruit almost completely.
Flowering summer-fall (almost year-round in tropics, subtropics). Waste places, fields, roadsides, other disturbed habitats; 0-1000 m.