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Argentina amaranth, deflexed amaranth, large-fruit amaranth, low amaranth

California amaranth, California pigweed, Californian amaranth

Habit Plants short-lived perennial or annual, pubescent in distal parts of plant or becoming glabrescent at maturity. Plants annual, glabrous.
Stems

ascending or prostrate, profusely branched basally, radiating from rootstock, mostly 0.2–0.5 m.

prostrate, whitish or tinged with red, much-branched from base, 0.1–0.5 m, rather fleshy.

Leaves

petiole 1/2 as long as to equaling blade;

blade rhombic-ovate or ovate to lanceolate, 1–2 × 0.5–1 cm, base tapering or cuneate, margins entire, plane or slightly undulate, apex subacute, obtuse, or retuse or shallowly emarginate, mucronulate.

petiole 1/2 or less as long as blade;

blade pale green, veins prominent, obovate, spatulate, or oblanceolate to linear, 0.3–2(–3) × 0.2–1.5 cm, base cuneate, margins entire, plane or slightly undulate, apex obtuse to subacute, with prominent mucro.

Bracts

of pistillate flowers linear, 0.5–1 mm, 1/2 as long as tepals.

of pistillate flowers linear, 0.5–1 mm, ± equaling tepals.

Inflorescences

terminal, erect, compact, pyramidal panicles and also some axillary clusters, green or silvery green, occasionally tinged with red, leafless at least distally.

axillary clusters borne from bases to tops of plants.

Staminate flowers

clustered at tips of inflorescences;

tepals 2–3;

stamens 2–3.

intermixed with pistillate;

tepals (2–)3;

stamens 3.

Pistillate flowers

tepals 2–3, narrowly elliptic or oblanceolate, not clawed, equal or subequal, 1.2–2 mm, apex broadly acute;

style branches erect;

stigmas 3.

tepals 1–3, narrowly lanceolate, unequal, usually with only 1 well-developed tepal, largest 1–1.2 mm, apex acute to acuminate;

stigmas 3.

Seeds

very dark brown to black, 1–1.2 mm diam., shiny, filling only proximal portion of fruit.

very dark reddish brown, lenticular, (0.6–)0.7–1 mm diam., shiny.

Utricles

marked with 2(–3) green lines that intersect at apex and divide fruit into halves or quarters, slightly to distinctly inflated, ellipsoid, 2–3 mm, distinctly longer than tepals, smooth (in dry plants wrinkled or rugose), indehiscent.

subglobose, 1–1.2 mm, smooth or wrinkled (especially in dry plants), dehiscence regularly circumscissile or tardily dehiscent.

Amaranthus deflexus

Amaranthus californicus

Phenology Flowering summer–fall. Flowering summer–fall.
Habitat Weedy areas, ballast heaps, railroads, other disturbed habitats Seasonally moist flats, shores of water bodies, waste places, other disturbed habitats
Elevation 0-500 m (0-1600 ft) 0-2800 m (0-9200 ft)
Distribution
from FNA
AL; CA; FL; GA; LA; MA; NJ; NY; OR; PA; TN; VA; native to South America [Introduced in North America; locally introduced or naturalized in tropical to warm-temperate regions of the globe]
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; ID; KS; MT; NE; NV; OR; SD; TX; UT; WA; WY; AB; SK
[WildflowerSearch map]
[BONAP county map]
Discussion

The hybrid between Amaranthus deflexus and A. muricatus was described from Europe as A. ×tarraconensis Sennen & Pau (see J. L. Carretero 1979) and may be expected in North America in the future in places of possible co-occurrence of the parental species.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 4, p. 430. FNA vol. 4, p. 431.
Parent taxa Amaranthaceae > Amaranthus > subg. Albersia Amaranthaceae > Amaranthus > subg. Albersia
Sibling taxa
A. acanthochiton, A. albus, A. arenicola, A. australis, A. blitoides, A. blitum, A. californicus, A. cannabinus, A. caudatus, A. crassipes, A. crispus, A. cruentus, A. dubius, A. fimbriatus, A. floridanus, A. graecizans, A. greggii, A. hybridus, A. hypochondriacus, A. muricatus, A. obcordatus, A. palmeri, A. polygonoides, A. powellii, A. pumilus, A. retroflexus, A. scleropoides, A. spinosus, A. tamaulipensis, A. thunbergii, A. torreyi, A. tricolor, A. tuberculatus, A. viridis, A. viscidulus, A. watsonii, A. wrightii
A. acanthochiton, A. albus, A. arenicola, A. australis, A. blitoides, A. blitum, A. cannabinus, A. caudatus, A. crassipes, A. crispus, A. cruentus, A. deflexus, A. dubius, A. fimbriatus, A. floridanus, A. graecizans, A. greggii, A. hybridus, A. hypochondriacus, A. muricatus, A. obcordatus, A. palmeri, A. polygonoides, A. powellii, A. pumilus, A. retroflexus, A. scleropoides, A. spinosus, A. tamaulipensis, A. thunbergii, A. torreyi, A. tricolor, A. tuberculatus, A. viridis, A. viscidulus, A. watsonii, A. wrightii
Synonyms Mengea californica
Name authority Linnaeus: Mant. Pl. 2: 295. (1771) (Moquin-Tandon) S. Watson: in W. H. Brewer et al., Bot. California 2: 42. (1880)
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