Amaranthus muricatus |
Amaranthus albus |
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African amaranth, muricate amaranth |
pigweed amaranth, prostrate pigweed, tumble pigweed, tumbleweed, tumbleweed amaranth, tumbling pigweed, white amaranth, white pigweed |
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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. 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. |
usually erect, ascending proximally, rarely almost prostrate, much-branched, bushy (large plants forming tumbleweeds), 0.1–1 m. Leaves: 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 |
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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 |
AL; s South America (Argentina, Paraguay, Uruguay) [Introduced in North America; introduced in s Europe, s Africa, Australia, and other regions] |
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]
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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 | ||
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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