Amaranthus blitoides |
Amaranthus fimbriatus |
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mat amaranth, matweed, matweed amaranth, procumbent pigweed, prostrate amaranth, prostrate pigweed, prostrate tumbleweed, tumbleweed amaranth |
fringe amaranth, fringe pigweed |
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Habit | Plants annual, glabrous. | Plants glabrous. |
Stems | prostrate or ascending (very rarely suberect), much-branched (usually from base), (0.1–)0.2–0.6(–1) m. Leaves: petiole ± 1/2 as long as blade; blade obovate, elliptic, or spatulate, 1–2(–4) × 0.5–1(–1.5) cm, base cuneate and tapering, margins usually entire, plane, rarely slightly undulate, apex obtuse, rounded, mucronulate. |
erect or with lateral branches ascending, usually branched from base, main and lateral stems sparingly branched or simple, 0.3–0.7(–1) m. Leaves short-petiolate; petiole 1/4–1/2 as long as blade; blade linear to narrowly lanceolate, (1–)2–6(–10) × 0.1–0.5(–1) cm, base narrowly cuneate, margins entire, plane, apex acute to mucronulate. |
Bracts | of pistillate flowers narrow, thin, 1.5–5 mm, ± equaling or slightly exceeding tepals. |
of pistillate flowers ovate to ovate-lanceolate, 1–1.8 mm, shorter than tepals, about 1/2 or less as long as tepals. |
Inflorescences | axillary glomerules, green. |
mostly axillary clusters scattered from base to apex of plants, distally condensed in lax, unbranched, almost leafless, slender, terminal spikes, interrupted. |
Staminate flowers | intermixed with pistillate; tepals 3(–4); stamens 3. |
tepals 5, apex obtuse; stamens (2–)3. |
Pistillate flowers | tepals (3–)4–5, narrowly ovate to broadly linear, unequal or subequal, 1.5–3 mm, thin, apex acute or acuminate; style branches spreading; stigmas 3. |
tepals 5, reflexed, fan-shaped to broadly spatulate, clawed, equal or subequal, 1.5–3.3 mm, margins fimbriate or denticulate, apex much expanded and obtuse; style branches erect to ± spreading; stigmas 3(–4). |
Seeds | black, lenticular to broadly plumply lenticular, 1.3–1.6 mm diam., rather dull. |
black or dark reddish brown, lenticular to broadly lenticular, 0.8–1 mm diam., shiny, smooth. |
Utricles | broadly ovoid, 1.7–2.5 mm, equaling tepals, mostly smooth (slightly verrucose or rugose in dry plants), dehiscence regularly circumscissile. |
subglobose to obovate, 1.2–2 mm, shorter than tepals, rugose to nearly smooth, dehiscence regularly circumscissile. |
2n | = 34. |
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Amaranthus blitoides |
Amaranthus fimbriatus |
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Phenology | Flowering summer–fall. | Flowering summer–fall (in arid regions mostly after summer rains). |
Habitat | Disturbed habitats: roadsides, riverbanks, railroads, fields, waste places, sandy flats | Sandy, gravelly slopes, washes, semideserts, disturbed habitats |
Elevation | 0-2200 m (0-7200 ft) | 500-1700 m (1600-5600 ft) |
Distribution |
AK; AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MT; 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; ON; QC; SK [Introduced and often completely naturalized in South America, Eurasia, and other regions]
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AZ; CA; NM; TX; UT; n Mexico
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Discussion | The name Amaranthus graecizans often has been misapplied to both A. blitoides and A. albus in older North American floras and manuals. Amaranthus blitoides was probably originally native to central and partly eastern United States, but now it is widely and successfully naturalized almost everywhere in temperate North America and in many subtropical to warm-temperate regions. It has not been reported from Mississippi or North Carolina but since it is found in all other conterminous United States it can be expected to occur in these two as well. Varieties have been described within Amaranthus blitoides; most of them are of no taxonomic significance, being mostly ecologic forms or local morphologic variants. Among the infraspecific taxa, the most constant is var. reverchonii Uline & W. L. Bray, with narrower, more elongated leaves. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Two varieties of Amaranthus fimbriatus have been recognized: var. fimbriatus, with tepals fimbriate at the apex, and var. denticulatus (= A. venulosus S. Watson), with denticulate or crenulate tepals. The latter is reported from Arizona and adjacent northern Mexico; it probably occurs more widely. A related species, Amaranthus chihuahuensis S. Watson, which occurs in Mexico (Chihuahua and Oaxaca), was reported from trans-Pecos Texas, but no reliable specimens were seen by C. F. Reed (1969b). The presence of that species in the United States needs confirmation, and its taxonomic identity remains obscure. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 4, p. 434. | FNA vol. 4. |
Parent taxa | Amaranthaceae > Amaranthus > subg. Albersia | Amaranthaceae > Amaranthus > subg. Amaranthus |
Sibling taxa | ||
Synonyms | Sarratia berlandieri var. fimbriata, A. fimbriatus var. denticulatus | |
Name authority | S. Watson: Proc. Amer. Acad. Arts 12: 273. (1877) | (Torrey) Bentham ex S. Watson: in W. H. Brewer et al., Bot. California 2: 42. (1880) |
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