Burke: Amaranthus muricatus vs. Amaranthus retroflexus

	Amaranthus muricatus	Amaranthus retroflexus
		redroot pigweed, rough pigweed
Habit		Dioecious, erect, simple to freely-branched annual 5-10 dm. tall, obviously pubescent.
Leaves		Leaves alternate, numerous, the blade lanceolate to obovate-oblanceolate, 2.5-8 cm. long, hairy on the lower surface, narrowed abruptly to petioles about as long.
Flowers		Flowers closely crowded in terminal and axillary, simple to compound spikes 2-10 cm. long, subtended by several lanceolate, spiny bracts 3.5-5 mm. long; sepals of the pistillate flowers spatulate to lanceolate, 2.5-4 mm. long, at lest twice as long as the ovary; petals none; stamens usually 5; styles 3.
Fruits		1-seeded capsule.

	Amaranthus muricatus	Amaranthus retroflexus
Flowering time		July-October
Habitat		Fields, roadsides, wastelots, and other disturbed areas.
Distribution	[BONAP county map]	Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across North America to the Atlantic Coast. [WildflowerSearch map] [BONAP county map]
Origin		Introduced from eastern and central North America
Conservation status		Not of concern
Sibling taxa	A. albus, A. blitoides, A. blitum, A. californicus, A. caudatus, A. cruentus, A. deflexus, A. hybridus, A. hypochondriacus, A. powellii, A. retroflexus, A. tuberculatus	A. albus, A. blitoides, A. blitum, A. californicus, A. caudatus, A. cruentus, A. deflexus, A. hybridus, A. hypochondriacus, A. powellii, A. tuberculatus
Web links	Local Web sites: 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: BC, 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 muricatus

Amaranthus retroflexus

redroot pigweed, rough pigweed

Habit

Dioecious, erect, simple to freely-branched annual 5-10 dm. tall, obviously pubescent.

Leaves

Leaves alternate, numerous, the blade lanceolate to obovate-oblanceolate, 2.5-8 cm. long, hairy on the lower surface, narrowed abruptly to petioles about as long.

Flowers

Flowers closely crowded in terminal and axillary, simple to compound spikes 2-10 cm. long, subtended by several lanceolate, spiny bracts 3.5-5 mm. long;

sepals of the pistillate flowers spatulate to lanceolate, 2.5-4 mm. long, at lest twice as long as the ovary;

petals none;

stamens usually 5;

styles 3.

Fruits

1-seeded capsule.