Amaranthus torreyi
Amaranthus albus
Bigelow's amaranth, sandhill amaranth, Torrey's amaranth, Torrey's amaranthus
pigweed amaranth, prostrate pigweed, tumble pigweed, tumbleweed, tumbleweed amaranth, tumbling pigweed, white amaranth, white pigweed
erect or ascending proximally, much-branched especially near base, 0.1–0.7 m. Leaves: petiole less than 1/2 as long as blade;
blade oblanceolate or lanceolate to ovate-lanceolate, (1.2–)1.5–5(–7) × 0.3–2 cm, base narrowly cuneate to cuneate, margins entire, plane or slightly undulate, apex acute to subobtuse, mucronulate.
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.
lanceolate to linear-subulate, 1.3–3.5 mm, slightly longer than tepals.
of pistillate flowers subulate to linear-lanceolate, narrow, 2–3 mm, 2 times as long as tepals.
axillary clusters, toward apex aggregated in spikes (rarely spicate panicles), axes, leafy (occasionally almost leafless distally).
axillary glomerules, green, whitish green, or yellowish.
mostly at tips of inflorescences;
tepals 5, equal or subequal;
stamens 3(–5).
intermixed with pistillate;
tepals 3;
stamens 3.
tepals 5, spatulate to narrowly spatulate, clawed, equal or subequal, 1.5–2.5 mm, margins entire, apex obtuse, rounded, or slightly emarginate;
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.
black, subglobose to broadly lenticular, 1 mm diam., smooth, shiny.
dark reddish brown to black, lenticular, 0.6–1 mm diam., shiny.
obovoid to subglobose-obovoid, 1.5–2 mm, nearly equaling or slightly shorter than tepals, smooth, dehiscence regularly circumscissile.
ellipsoid-ovoid, 1.5 mm, equaling or exceeding tepals, smooth proximally, coarsely rugose distally, dehiscence regularly circumscissile.
Amaranthus torreyi
Amaranthus albus
The name Amaranthus torreyi has been widely misapplied to at least two other species, 7. A. arenicola and 6. A. watsonii. Because of that, the name A. bigelovii was used for A. torreyi by J. D. Sauer (1955) and in some recent floras. Sometimes A. torreyi (California and Arizona) and A. bigelovii (New Mexico and Texas) are recognized as separate species. The nomenclature and taxonomic relationships in this group should be critically reviewed based on type specimens and additional experimental and field studies.
(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.)
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
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MD Biodiversity, 
MI Flora, 
MN Wildflowers, 
MO Plants, 
PNW Herbaria 
WildflowerSearch
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