Amaranthus blitoides
Amaranthus blitum
mat amaranth, matweed, matweed amaranth, procumbent pigweed, prostrate amaranth, prostrate pigweed, prostrate tumbleweed, tumbleweed amaranth
Guernsey pigweed, livid amaranth, pale amaranth, purple amaranth
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.
ascending to prostrate, sometimes erect, simple or branched, sometimes radiating from base and forming mats, 0.1–0.6 m. Leaves: petiole usually equaling to 2 times as long as blade;
blade ovate or obovate, 1–6 × 0.5–4 cm, base tapering or cuneate, margins entire, plane, apex distinctly emarginate to almost bilobate, mucronate.
of pistillate flowers narrow, thin, 1.5–5 mm, ± equaling or slightly exceeding tepals.
of pistillate flowers lanceolate, inconspicuous, 0.5 mm, shorter than tepals.
axillary glomerules, green.
slender terminal spikes or panicles and also axillary clusters, in some forms only axillary clusters are present;
spikes erect or sometimes reflexed, green, leafless at least distally.
intermixed with pistillate;
tepals 3(–4);
stamens 3.
clustered at tips of spikes;
tepals 3;
stamens 3.
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 3, elliptic or spatulate, not clawed, equal or subequal, 0.8–1.5 mm, margins entire, apex broadly acute;
style branches erect;
stigmas 3.
black, lenticular to broadly plumply lenticular, 1.3–1.6 mm diam., rather dull.
black or dark reddish brown, subglobose or broadly lenticular, (0.8–)1–1.8 mm diam., smooth, shiny, filling fruit almost completely.
broadly ovoid, 1.7–2.5 mm, equaling tepals, mostly smooth (slightly verrucose or rugose in dry plants), dehiscence regularly circumscissile.
compressed, subglobose to obovate, 1.2–2.5(–3) mm, exceeding tepals, smooth or faintly rugose, indehiscent.
Amaranthus blitoides
Amaranthus blitum
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.)
The name Amaranthus lividus has been widely used for A. blitum, in addition to other Linnaean names (see F. Fillias et al. 1980; J. P. M. Brenan and C. C. Townsend 1980; R. K. Brummitt 1984). Amaranthus blitum is of tropical origin and not common in temperate regions. It has been cultivated in Europe as a minor leaf-vegetable crop, but now it is declining and its range is becoming progressively smaller. In many temperate countries (in particular in Europe), A. blitum persists mostly as an uncommon and sporadic weed in greenhouses, ornamental gardens, and flower beds.
In Europe, it may be possible to distinguish two or three subspecies within Amaranthus blitum. The occurrence and distribution of infraspecific taxa of the A. blitum complex is insufficiently known in North America and requires additional floristic and taxonomic studies, although it appears that the most common is subsp. polygonoides (Moquin-Tandon) Cattetero. Some literature records of A. blitum from southern regions of North America are misidentifications of A. viridis, and vice versa; because of that the distributions of these two species in the flora area require critical reassessment.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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