OregonFlora: Amaranthus hybridus vs. Amaranthaceae

	Amaranthus hybridus	Amaranthaceae
	slender pigweed, slim amaranth	amaranth family
Habit	Plants mostly glabrous, villous distally when young.	Herbs, subshrubs, or shrubs annual or perennial, monoecious or dioecious, glabrous, pubescent, often farinose, sometimes succulent.
Stems	erect, branched or not, 3–12(20) dm, green or red.	erect, ascending, prostrate or spreading, often much branched, sometimes fleshy and jointed.
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.	mostly alternate, sometimes opposite distally; simple, sometimes greatly reduced; margins entire, toothed, or hastate-lobed.
Inflorescences	terminal and axillary, tightly clustered; lax and nodding; dull green to red, villous; bracts 2–4 mm; midveins extending to a spine.	axillary or terminal, commonly spikes or panicles, or sometimes solitary, with or without bracts.
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.	small and inconspicuous, unisexual or bisexual; perianths present or sometimes absent; corollas lacking; filaments free or united at bases; nectaries sometimes present in bisexual flowers; pistils with 1–3(5) carpels; ovaries with 1 cell and 1 ovule; superior or occasionally partially inferior, sometimes subtended by fruiting bracteoles.
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.	utricles or achenes.
Seeds	lenticular, widely orbicular to rounded, 1–1.4 mm, red-brown to black; shiny.	1; vertical or horizontal in relation to infructescence axis; small, usually lenticular to globose.
2n	=32.

	Amaranthus hybridus	Amaranthaceae
Distribution	[WildflowerSearch map] [BONAP county 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.	Worldwide. ~165 genera; 18 genera treated in Flora. This family contains many plants of economic importance, including beets, chard, and spinach, as well as cereal grains and animal fodder crops. Beta vulgaris has been occasionally reported as a short-lived waif. It has not, however, become naturalized in our region. Both the phylogenetic and morphological work support the expansion of Amaranthaceae to include former members of Chenopodiaceae (Stevens 2012). Following a recent molecular study of Sarcobatus (Cuénoud et al. 2008), the genus has been assigned to a separate family, Sarcobataceae.
Source	Flora of Oregon, volume 2, page 66 Bridget Chipman	Flora of Oregon, volume 2, page 62
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	Local floras: CA, OR Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Amaranthaceae

slender pigweed, slim amaranth

amaranth family

Habit

Plants mostly glabrous, villous distally when young.

Herbs, subshrubs, or shrubs annual or perennial, monoecious or dioecious, glabrous, pubescent, often farinose, sometimes succulent.

Stems

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

erect, ascending, prostrate or spreading, often much branched, sometimes fleshy and jointed.

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.

mostly alternate, sometimes opposite distally; simple, sometimes greatly reduced;

margins entire, toothed, or hastate-lobed.

Inflorescences

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

bracts 2–4 mm;

midveins extending to a spine.

axillary or terminal, commonly spikes or panicles, or sometimes solitary, with or without bracts.

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.

small and inconspicuous, unisexual or bisexual;

perianths present or sometimes absent;

corollas lacking;

filaments free or united at bases;

nectaries sometimes present in bisexual flowers;

pistils with 1–3(5) carpels;

ovaries with 1 cell and 1 ovule; superior or occasionally partially inferior, sometimes subtended by fruiting bracteoles.

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.

utricles or achenes.

Seeds

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

1; vertical or horizontal in relation to infructescence axis; small, usually lenticular to globose.

=32.

Amaranthaceae

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.

Worldwide. ~165 genera; 18 genera treated in Flora.

This family contains many plants of economic importance, including beets, chard, and spinach, as well as cereal grains and animal fodder crops. Beta vulgaris has been occasionally reported as a short-lived waif. It has not, however, become naturalized in our region. Both the phylogenetic and morphological work support the expansion of Amaranthaceae to include former members of Chenopodiaceae (Stevens 2012). Following a recent molecular study of Sarcobatus (Cuénoud et al. 2008), the genus has been assigned to a separate family, Sarcobataceae.

Source

Flora of Oregon, volume 2, page 66
Bridget Chipman

Flora of Oregon, volume 2, page 62

Sibling taxa