OregonFlora: Amaranthus hybridus

	Amaranthus hybridus
	slender pigweed, slim amaranth
Habit	Plants mostly glabrous, villous distally when young.
Stems	erect, branched or not, 3–12(20) dm, green or red.
Leaves	blades rhombic-ovate to widely lanceolate; (2)4–12(15) cm, bases wedge-shaped; margins entire; plane; tips acute to obtuse; midveins extending to a spine; petioles 1–5(10) cm.
Inflorescences	terminal and axillary, tightly clustered; lax and nodding; dull green to red, villous; bracts 2–4 mm; midveins extending to a spine.
Flowers	perianth segments 5, mostly similar in staminate and pistillate flowers; erect, not overlapping or reflexed, linear to lance-oblong; midveins extending to spine; tips acute.
Staminate flowers	generally at inflorescence tips; perianth segments of nearly equal length, 2–3 mm; stamens 5.
Pistillate flowers	perianth segments of equal length or 1 slightly longer, 1.5–2 mm; styles 3; erect.
Fruits	ovoid, 1.5–2.2 mm, rugose at tips; smooth below; dehiscence circumscissile.
Seeds	lenticular, widely orbicular to rounded, 1–1.4 mm, red-brown to black; shiny.
2n	=32.

	Amaranthus hybridus
Distribution	[WildflowerSearch map] [BONAP county map]
Discussion	Disturbed areas, streambanks, roadsides, fields. Flowering May–Oct. 0–700 m. Casc, Owy, Sisk, WV. CA, ID, NV, WA; throughout North America; scattered worldwide. Native? Amaranthus hybridus has been known to hybridize with A. retroflexus.
Source	Flora of Oregon, volume 2, page 66 Bridget Chipman
Sibling taxa	A. albus, A. blitoides, A. californicus, A. deflexus, A. hypochondriacus, A. powellii, A. retroflexus, A. viridus
Web links	Local floras: CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Amaranthus hybridus

slender pigweed, slim amaranth

Habit

Plants mostly glabrous, villous distally when young.

Stems

erect, branched or not, 3–12(20) dm, green or red.

Leaves

blades rhombic-ovate to widely lanceolate; (2)4–12(15) cm, bases wedge-shaped;

margins entire; plane;

tips acute to obtuse;

midveins extending to a spine;

petioles 1–5(10) cm.

Inflorescences

terminal and axillary, tightly clustered; lax and nodding; dull green to red, villous;

bracts 2–4 mm;

midveins extending to a spine.

Flowers

perianth segments 5, mostly similar in staminate and pistillate flowers; erect, not overlapping or reflexed, linear to lance-oblong;

midveins extending to spine;

tips acute.

Staminate flowers

generally at inflorescence tips;

perianth segments of nearly equal length, 2–3 mm;

stamens 5.

Pistillate flowers

perianth segments of equal length or 1 slightly longer, 1.5–2 mm;

styles 3; erect.

Fruits

ovoid, 1.5–2.2 mm, rugose at tips; smooth below; dehiscence circumscissile.

Seeds

lenticular, widely orbicular to rounded, 1–1.4 mm, red-brown to black; shiny.

=32.

Amaranthus hybridus

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

Disturbed areas, streambanks, roadsides, fields. Flowering May–Oct. 0–700 m. Casc, Owy, Sisk, WV. CA, ID, NV, WA; throughout North America; scattered worldwide. Native?

Amaranthus hybridus has been known to hybridize with A. retroflexus.

Source

Flora of Oregon, volume 2, page 66
Bridget Chipman

Sibling taxa