Plants annual or short-lived perennial, glabrous or slightly pubescent near tips. Stems ascending or prostrate, much-branched from stout rootstock, 0.1-0.4 m. Leaves: petiole to ¹/2 as long as blade; blade linear to narrowly lanceolate, 1.5-8 × 0.2-0.5(-1) mm, base tapering, margins entire, plane to undulate, apex obtuse and often emarginate. Inflorescences terminal, compact pyramidal panicles and axillary glomerules, erect or reflexed, green, leafless at least distally. Bracts of pistillate flowers linear, 0.7-1.2 mm, ¹/2-²/3 as long as tepals. Pistillate flowers: tepals 5, narrowly oblanceolate, not clawed, equal, 1.5-2 mm, apex obtuse or subacute; style branches erect; stigmas 3. Staminate flowers intermixed with pistillate or at tips of inflorescences; tepals 5; stamens 5. Utricles compressed, subglobose, 1.7-2 mm, ± equaling or slightly exceeding tepals, muricate, indehiscent. Seeds black, lenticular, 1-1.2 mm diam., semiglossy.

Flowering summer-fall. Waste places, on ballast; 0 m; introduced; Ala.; s South America (Argentina, Paraguay, Uruguay); introduced in s Europe, s Africa, Australia, and other regions.