Amaranthus viridis L.

Annual herb, erect or more rarely ascending, 10-75 (-100) cm. Stem rather slender, sparingly to considerably branched, angular, glabrous or more frequently increasingly hairy upwards (especially in the inflorescence) with short or longer and rather floccose multicellular hairs. Leaves glabrous or shortly to fairly long-pilose on the lower surface of the primary and most of the venation, long-petiolate (petioles up to c. 10 cm long and the longest commonly longer than the lamina), lamina deltoid-ovate to rhomboid-oblong, 2-7 x 1.5-5.5 cm, the margins occasionally obviously sinuate, shortly cuneate to sub-truncate below, obtuse and narrowly to clearly emarginate at the tip, minutely mucronate. Flowers green, in slender, axillary or terminal, often paniculate spikes c. 2.5-12 cm long and 2-5 mm wide, or in the lower part of the stem in dense axillary clusters to c. 7 mm in diameter; male and female flowers intermixed but the latter more numerous. Bracts and bracteoles deltoid-ovate to lanceolate-ovate, whitish-membranous with a very short, pale or reddish awn formed by the excurrent green midrib, bracteoles shorter than the perianth (c. 1 mm.). Perianth segments 3, very rarely 4, those of the male flowers oblong-oval, acute, concave, c. 1.5 mm, shortly mucronate; those of the female flowers narrowly oblong to narrowly spathulate, finally 1.25-1.75 mm, minutely mucronate or not, the borders white-membranous, midrib green and often thickened above. Stigmas 2-3, short, erect or almost so. Capsule subglobose, 1.25-1.5 mm, not or slightly exceeding the perianth, indehiscent or rupturing irregularly, very strongly rugose throughout. Seed c. 1-1.25 mm, round, only slightly compressed, dark brown to black with an often paler thick border, ± shining, reticulate and with shallow scurfy verrucae on the reticulum, the verrucae with the shape of the areolae.

Plants annual, sometimes short-lived perennial in tropics and subtropics, glabrous. Stems erect, simple or with lateral branches (especially distally), 0.2-1 m. Leaves: petiole ¹/2-1¹/2 as long as blade; blade rhombic-ovate or ovate, 1-7 × 0.5-5 cm, base rounded, cuneate, or attenuate, margins entire, plane, apex obtuse, rounded, or emarginate, mucronate. Inflorescences slender spikes aggregated into elongate terminal panicles, also from distal axils, green, leafless at least distally. Bracts of pistillate flowers ovate to lanceolate, 1 mm, shorter than tepals. Pistillate flowers: tepals 3, narrowly elliptic, obovate-elliptic or spatulate, not clawed, ± equal, 1.2-1.7 mm, apex rounded or nearly acute, mucronate or not; style branches erect; stigmas 3. Staminate flowers inconspicuous, mostly at tips of inflorescences; tepals 3; stamens 3. Utricles ovoid to compressed-ovoid, 1-1.6 mm, equaling or slightly exceeding tepals, prominently or faintly rugose, indehiscent. Seeds black or dark brown, subglobose to thick-lenticular, 1 mm diam., minutely punctulate, rather dull.

Stem erect, green or somewhat tinged purple, 40-80 cm tall, conspicuously angulate, slightly branched, glabrous. Petiole 3-6 cm, green or somewhat tinged purple; leaf blade ovate, ovate-oblong, or ovate-elliptic, 3-9 × 2.5-6 cm, base broadly cuneate or subtruncate, margin entire or slightly undulate, apex notched or rounded, with a pointed mucro. Complex thyrsoid structures terminal, 6-12 × 1.5-3 cm, branched, composed of spikes; spikes erect, slender, terminal ones longer than lateral ones; rachis 2-2.5 cm. Bracts and bracteoles lanceolate, shorter than 1 mm, apex pointed. Tepals oblong or broadly oblanceolate, 1.2-1.5 mm, apex acute. Stamens shorter than perianth; stigmas 3 or 2. Utricles green, longer than perianth, globose, slightly compressed, ca. 2 mm in diam., very rugose, indehiscent. Seeds black or brownish black, subglobose, ca. 1 mm in diam. Fl. Jun-Aug, fr. Aug-Oct. 2n = 34.

Pantropical.

Distribution: Perhaps the most widely distributed and common species of the genus, found throughout the tropical and subtropical regions of the world, and penetrating further into the temperate regions than most of the tropical species. A common weed of waste and cultivated ground in Pakistan, ascending to at least 1220 m.

introduced; Ala., Ariz., Ark., Fla., Ga., La., Mass., Mich., Miss., N.Mex., N.Y., N.C., Okla., Pa., S.C., Tenn., Tex., Va.; native to South America; introduced in tropical and subtropical regions worldwide.

150-1200 m

Flowering summer-fall.

Fields, railroads, lawns, gardens, waste areas, other disturbed habitats; 0-1000m.

Fields, waste places. All provinces except for NW China and Xizang [pantropical].

Amaranthus gracilis Desfontaines ex Poiret

Euxolus viridis (Linnaeus) Moquin-Tandon.