Amaranthus hybridus
Amaranthus blitoides
green amaranth, green pigweed, hybrid amaranth, slender pigweed, slim amaranth, smooth amaranth, smooth pigweed
mat amaranth, matweed, matweed amaranth, procumbent pigweed, prostrate amaranth, prostrate pigweed, prostrate tumbleweed, tumbleweed amaranth
erect, green or sometimes reddish purple, rarely under-developed plants ascending, branched to nearly simple, 0.3–2(–2.5) m.
prostrate or ascending (very rarely suberect), much-branched (usually from base), (0.1–)0.2–0.6(–1) m.
petiole 1/2 as long as to equaling blade;
blade ovate, rhombic-ovate, or lanceolate, (2–)4–15 × (1–)2–6 cm, base cuneate to broadly cuneate, margins entire, apex acute to obtuse, with mucro.
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.
lanceolate-linear to subulate, 2–3.5(–4) mm, subequal to or 2 times as long as tepals, apex spinescent.
of pistillate flowers narrow, thin, 1.5–5 mm, ± equaling or slightly exceeding tepals.
terminal and axillary, erect or reflexed, occasionally nodding, green or olive green, occasionally with silvery or reddish purple tint, leafless at least distally, terrminal inflorescence often slightly nodding with numerous shorter branches at base.
axillary glomerules, green.
at tips of inflorescences;
tepals 5;
stamens (4–)5.
intermixed with pistillate;
tepals 3(–4);
stamens 3.
tepals 5, lanceolate to lanceolate-linear, subequal or unequal, 1.5–3 mm, membranaceous, apex acute or acuminate, gradually narrowing into aristate tip;
style branches erect, shorter than body of fruit;
stigmas 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.
black to dark reddish brown, lenticular to lenticular-globose, 1–1.3 mm, smooth, shiny.
black, lenticular to broadly plumply lenticular, 1.3–1.6 mm diam., rather dull.
obovoid or elongate-ovoid, 1.5–2.5 mm, shorter than tepals, smooth proximally, lid verrucose or rugose, dehiscence regularly circumscissile, or rarely in some presumably hybrid forms, irregularly dehiscent or indehiscent.
broadly ovoid, 1.7–2.5 mm, equaling tepals, mostly smooth (slightly verrucose or rugose in dry plants), dehiscence regularly circumscissile.
Amaranthus hybridus
Amaranthus blitoides
Originally a riverside pioneer in eastern North America, now Amaranthus hybridus is extremely abundant in agricultural fields and other disturbed habitats. Related cultivated species have been reported from the flora area, including A. caudatus, A. hypochondriacus, and A. cruentus; there is no evidence that they are established; specimens identified as these species are often variants of A. hybridus.
Distribution of Amaranthus hybridus in North America needs clarification because the name was misapplied to other species, notably A. powellii, and specimens of A. retroflexus, A. powellii, and A. hybridus are frequently interchangeably misidentified. Forms of A. hybridus and A. powellii with reddish inflorescences are often misidentified as escaped and hence presumably naturalized, cultivated species A. caudatus Linnaeus, A. hypochondriacus Linnaeus, and A. cruentus Linnaeus.
Amaranthus hybridus is extremely variable. In particular, there are numerous North American specimens with subobtuse tepals and thick inflorescences, suggesting hybridization with A. retroflexus. In Europe such presumably hybrid forms are known as A. ×ozanonii Thellung (A. Thellung 1914–1919).
A new, presumably hybridogenous taxon, Amaranthus ×tucsonensis Henrickson, was recently described from Arizona (J. Henrickson 1999). It was suggested that one of its parents is A. hybridus; the other parental species (probably a species with obtuse or spatulate tepals) remains unknown. The problem of proper taxonomic position and origin of A. ×tucsonensis needs further study.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
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BC, CA, OR, WA - Local Web sites: CalFlora, CalPhotos, Flora NW, Go Botany, IL Wildflowers, KS Wildflowers, LA Plants, MD Biodiversity, MI Flora, MN Wildflowers, MO Plants, PNW Herbaria
- WildflowerSearch
- iNaturalist (observations)
- USDA Plants Database
- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
