Amaranthus cruentus
Amaranthus australis
blood amaranth, caterpillar amaranth, purple amaranth, red amaranth
southern amaranth, southern water-hemp
erect, green or reddish purple, branched distally, mostly in inflorescence, to nearly simple, 0.4–2 m. Leaves: petiole 1/2 as long as to ± equaling blade;
blade rhombic-ovate or ovate to broadly lanceolate, 3–15(–20) × 1.5–10(–15) cm, occasionally larger in robust plants, base cuneate to broadly cuneate, margins entire, plane, apex acute or subobtuse to slightly emarginate, with mucro.
erect, branched, stout to robust, usually 1.5–3 m (occasionally to 9 m!) × 30 cm.
petiole 1/3–2/3 length of blade;
blade narrowly lanceolate to narrowly ovate, 10–20 × 1–4 cm, base cuneate, margins entire, plane, apex acute or long-attenuate to acuminate.
narrowly spathulate, 2–3 mm, equaling or slightly longer than tepals, apex short-spinescent.
of pistillate flowers 1.5–2 mm; of staminate flowers with moderately heavy midribs, 1.5–2 mm.
terminal and axillary, erect, reflexed, or nodding, usually dark red, purple, or deep beet-red, less commonly almost green or greenish red, leafless at least distally, large and robust.
mostly terminal, linear spikes to panicles, usually interrupted.
at tips of inflorescences;
tepals 5;
stamens (4–)5.
tepals 5, inner tepals with moderately prominent, excurrent midribs, equal, 2–2.5 mm, apex subacute to mucronulate;
stamens 5.
tepals 5, oblong to lanceolate, not clawed, equal or subequal, 1.5–3 mm, apex acute;
style branches erect or slightly reflexed;
stigmas 3.
tepals absent;
style branches spreading;
stigmas 3–5.
usually white or ivory, with reddish or yellowish tint, sometimes dark brown to dark reddish brown, broadly lenticular to elliptic-lenticular, 1.2–1.6 mm diam., smooth or indistinctly punctate.
reddish brown to dark brown, 1–1.2 mm diam., shiny.
obovoid to elongate-obovoid, 2–2.5 mm, smooth or slightly rugose distally, dehiscence regularly circumscissile.
stramineous to brown, with 3(–5) longitudinal ridges corresponding to 3–5 style branches, elliptic or obovoid, 1.5–2.5 mm, slightly fleshy, smooth (slightly rugose in herbarium specimens).
Amaranthus cruentus
Amaranthus australis
Amaranthus cruentus is cultivated as ornamental and pseudocereal almost worldwide from tropical to warm-temperate regions. While reported as naturalized in several states, most specimens identified as this species are referable to A. hybridus or other native species. Escaped plants of A. cruentus sometimes occur near places of cultivation (see note under A. caudatus). No attempt has been made to summarize distribution data for such escapes.
Amaranthus cruentus originated from A. hybridus (most probably in cultivation in Central America), with which it shares almost all major morphologic characteristics. Inclusion of cultivated forms in A. hybridus in a broad sense is thus rather justified. Cultivated species traditionally have been treated as separate taxa in horticultural and agricultural literature, and we prefer to maintain the current convenient usage of these names.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Plants of Amaranthus australis, a herbaceous annual, can be amazingly tall, with a single hollow main stem, up to 9 m, and the stem base can reach 30 cm in diameter. Large plants may somewhat resemble young trees of Taxodium distichum var. imbricarium, pondcypress.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
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WA - Local Web sites: CalFlora, CalPhotos,
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MI Flora, 
PNW Herbaria 
WildflowerSearch
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