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African amaranth, muricate amaranth

pigweed amaranth, prostrate pigweed, tumble pigweed, tumbleweed, tumbleweed amaranth, tumbling pigweed, white amaranth, white pigweed

Habit Plants annual or short-lived perennial, glabrous or slightly pubescent near tips. Plants annual, glabrous or glabrescent or viscid-pubescent.
Stems

ascending or prostrate, much-branched from stout rootstock, 0.1–0.4 m.

usually erect, ascending proximally, rarely almost prostrate, much-branched, bushy (large plants forming tumbleweeds), 0.1–1 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.

petiole 1/2 as long as blade, or longer in young proximal leaves;

blade obovate to narrowly spatulate, mostly 0.5 × 0.5–1.5 cm, early proximal leaves to 8 cm, base tapering, narrowly cuneate, margins entire, plane (or ± distinctly undulate), apex obtuse, with whitish or yellowish, subspinescent mucro.

Bracts

of pistillate flowers linear, 0.7–1.2 mm, 1/2–2/3 as long as tepals.

of pistillate flowers subulate to linear-lanceolate, narrow, 2–3 mm, 2 times as long as tepals.

Inflorescences

terminal, compact pyramidal panicles and axillary glomerules, erect or reflexed, green, leafless at least distally.

axillary glomerules, green, whitish green, or yellowish.

Staminate flowers

intermixed with pistillate or at tips of inflorescences;

tepals 5;

stamens 5.

intermixed with pistillate;

tepals 3;

stamens 3.

Pistillate flowers

tepals 5, narrowly oblanceolate, not clawed, equal, 1.5–2 mm, apex obtuse or subacute;

style branches erect;

stigmas 3.

tepals 3, narrowly ovate to linear, slightly unequal, 1–1.5 mm, thin, apex acute;

style branches erect;

stigmas 3.

Seeds

black, lenticular, 1–1.2 mm diam., semiglossy.

dark reddish brown to black, lenticular, 0.6–1 mm diam., shiny.

Utricles

compressed, subglobose, 1.7–2 mm, ± equaling or slightly exceeding tepals, muricate, indehiscent.

ellipsoid-ovoid, 1.5 mm, equaling or exceeding tepals, smooth proximally, coarsely rugose distally, dehiscence regularly circumscissile.

Amaranthus muricatus

Amaranthus albus

Phenology Flowering summer–fall. Flowering summer–fall.
Habitat Waste places, on ballast Disturbed habitats, waste places, vacant areas, railroads, streambanks, sandy areas, roadsides, agricultural fields
Elevation 0 m (0 ft) 0-2200 m (0-7200 ft)
Distribution
from FNA
AL; s South America (Argentina, Paraguay, Uruguay) [Introduced in North America; introduced in s Europe, s Africa, Australia, and other regions]
[BONAP county map]
from FNA
AK; AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NL; NS; ON; PE; QC; SK; SPM; Mexico [Introduced in North America; introduced and often successfully naturalized in South America, Eurasia, Africa, Australia]
[WildflowerSearch map]
[BONAP county map]
Discussion

The vernacular name “African amaranth” is sometimes used for this species; it is a misnomer; the species is native to South America and naturalized in Africa.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

The name Amaranthus graecizans, which refers to a species of Old World origin, has been misapplied to both A. albus and A. blitoides in earlier North American floras and manuals.

Southwestern plants differing from typical Amaranthus albus in having viscid pubescence and usually distinctly crisped leaf margins may be recognized as var. pubescens; they were occasionally treated as a separate species, A. pubescens.

Amaranthus albus and A. blitoides are rather often confused in herbaria. The species are easily distinguished by their seed size and luster.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 4, p. 431. FNA vol. 4.
Parent taxa Amaranthaceae > Amaranthus > subg. Albersia Amaranthaceae > Amaranthus > subg. Albersia
Sibling taxa
A. acanthochiton, A. albus, A. arenicola, A. australis, A. blitoides, A. blitum, A. californicus, A. cannabinus, A. caudatus, A. crassipes, A. crispus, A. cruentus, A. deflexus, A. dubius, A. fimbriatus, A. floridanus, A. graecizans, A. greggii, A. hybridus, A. hypochondriacus, A. obcordatus, A. palmeri, A. polygonoides, A. powellii, A. pumilus, A. retroflexus, A. scleropoides, A. spinosus, A. tamaulipensis, A. thunbergii, A. torreyi, A. tricolor, A. tuberculatus, A. viridis, A. viscidulus, A. watsonii, A. wrightii
A. acanthochiton, A. arenicola, A. australis, A. blitoides, A. blitum, A. californicus, A. cannabinus, A. caudatus, A. crassipes, A. crispus, A. cruentus, A. deflexus, A. dubius, A. fimbriatus, A. floridanus, A. graecizans, A. greggii, A. hybridus, A. hypochondriacus, A. muricatus, A. obcordatus, A. palmeri, A. polygonoides, A. powellii, A. pumilus, A. retroflexus, A. scleropoides, A. spinosus, A. tamaulipensis, A. thunbergii, A. torreyi, A. tricolor, A. tuberculatus, A. viridis, A. viscidulus, A. watsonii, A. wrightii
Synonyms Euxolus muricatus A. albus var. pubescens, A. pubescens
Name authority (Moquin-Tandon) Hieronymus: Pl. Diaph. Fl. Argent., 227. (1882) Linnaeus: Syst. Nat. ed. 10, 2: 1268. (1759)
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