Plants glabrous or moderately pubescent toward inflorescences, becoming glabrescent at maturity. Stems usually erect, green or sometimes reddish purple, branched, mainly in inflores-cences, to nearly simple, 0.3-1.5(-2) m, stiff. Leaves: petiole mostly equaling or longer than blade; blade rhombic-ovate to broadly lanceolate, 4-8 × 2-3 cm, occasionally larger in robust plants, base cuneate to broadly cuneate, margins entire, apex cuneate to obtuse or indistinctly emarginate, with mucro. Inflorescences mostly terminal, usually with spikes at distal axils, erect and rigid, green to silvery green, occasionally tinged red, leafless at least distally. Bracts lanceolate to linear-subulate, 4-7 mm, 2-3 times as long as tepals, rigid. Pistillate flowers: tepals usually 3-5, not clawed, unequal; outer tepals narrowly ovate-elliptic or elliptic, 1.5-3.5 mm, apex aristate; style branches spreading, shorter than body of fruit; stigmas 3. Staminate flowers clustered at tips of inflorescence branches; tepals 3-5; stamens 3-5. Utricles subglobose or compressed-ovoid, 2-3 mm, equaling or shorter than tepals, smooth or lid slightly rugose or minutely verrucose, dehiscence regularly circumscissile. Seeds black, subglobose to lenticular, 1-1.4 mm diam., smooth, shiny. Flowering summer-fall. Disturbed habitats, agricultural fields, railroads, roadsides, waste areas, banks of rivers, lakes, and streams; 0-2500 m; Alta., B.C., Ont., P.E.I., Que., Sask.; Ariz., Ark., Calif., Colo., Conn., Fla., Idaho, Ill., Ind., Kans., Ky., La., Maine, Mass., Mich., Minn., Miss., Mo., Mont., Nev., N.H., N.J., N.Mex., N.Y., N.C., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; Mexico; introduced or naturalized in South America, Eurasia, Australia. Amaranthus powellii is originally native to southwestern United States and adjacent regions of Mexico; now, it is widely naturalized almost everywhere in temperate regions of North America. The distribution of A. powellii is probably underestimated both in North America and the Old World, and literature references are somewhat confusing, because A. powellii has been commonly confused with A. hybridus.
Plant: Annual herb, erect, 3-20 dm, monoecious Leaves: petiole 10-50 mm; blade 15-90 mm, lower diamond-shaped to ovate, upper ± lanceolate INFLORESCENCE: panicle of spike-like clusters 1-1.8 cm wide; axillary clusters 1-6 cm; terminal clusters < or = 25 cm; bracts 3-6(8) mm, spine-tipped, midrib green, thick, margin scarious in lower 2/3 Flowers: Staminate flower: sepals 4-5, 2-3 mm; stamens 3-5; Pistillate flower: sepals 5, 1.7-3.6 mm, unequal, ± oblong, tip short-pointed Fruit: 2.5-3.6 mm, circumscissile, smooth throughout; Seed 0.8-1.4 mm wide, reddish black Misc: Waste places; < 800 m; Jul-Oct