Burke: Amaranthus muricatus vs. Amaranthus albus

	Amaranthus muricatus	Amaranthus albus
		white pigweed, tumbleweed
Habit		Annual herb, glabrous or becoming glabrous, or sticky-pubescent; stems typically erect or rarely nearly prostrate, up to 1 m, usually heavily branched, typically green, or white when dry, somewhat to greatly woolly towards ends of stems.
Leaves		Leaves alternate, petiolate, petiole 5-40 mm; blade obovate to narrowly spoon-shaped, base narrowly cuneate, apex obtuse to acute, margins entire and may be flat or occasionally wavy; cauline leaves 40-80 mm long and 15-30 mm broad, usually deciduous and replaced by axillary leaves, 7-20 mm long and 3-10 mm broad.
Inflorescence		Inflorescence a cymose axillary cluster, green, 3-flowered; bracts 1, 1.5-4 mm, generally 1.5-2 times the perianth, linear-lanceolate to awl-shaped, tip somewhat spined.
Flowers		Staminate flowers dispersed among pistillate flowers, perianth parts 3, stamens 3, filaments free, anthers 4-locular; pistillate flowers perianth parts 3, to 2 mm, oblong-lanceolate to linear, tip acute, stigmas 3 and erect, ovary ovoid, styles absent.
Fruit		Utricles dehiscing along a fissure encircling the whole fruit, 1.5-2 mm, larger than or equal to perianth, ellipsoid-ovoid, greenish white to brown, wrinkled especially near tip; seed approximately 1 mm, lenticular, reddish brown, smooth, shiny.

	Amaranthus muricatus	Amaranthus albus
Flowering time		June-September
Habitat		Dry, disturbed areas.
Distribution	[BONAP county map]	Occurring chiefly east of the Cascades crest in Washington; British Columbia to California, east across much of North America to the Atlantic Coast. [WildflowerSearch map] [BONAP county map]
Origin		Introduced from tropical 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. blitoides, A. blitum, A. californicus, A. caudatus, A. cruentus, A. deflexus, A. hybridus, A. hypochondriacus, A. powellii, A. retroflexus, 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 albus

white pigweed, tumbleweed

Habit

Annual herb, glabrous or becoming glabrous, or sticky-pubescent; stems typically erect or rarely nearly prostrate, up to 1 m, usually heavily branched, typically green, or white when dry, somewhat to greatly woolly towards ends of stems.

Leaves

Leaves alternate, petiolate, petiole 5-40 mm;

blade obovate to narrowly spoon-shaped, base narrowly cuneate, apex obtuse to acute, margins entire and may be flat or occasionally wavy;

cauline leaves 40-80 mm long and 15-30 mm broad, usually deciduous and replaced by axillary leaves, 7-20 mm long and 3-10 mm broad.

Inflorescence

Inflorescence a cymose axillary cluster, green, 3-flowered;

bracts 1, 1.5-4 mm, generally 1.5-2 times the perianth, linear-lanceolate to awl-shaped, tip somewhat spined.

Flowers

Staminate flowers dispersed among pistillate flowers, perianth parts 3, stamens 3, filaments free, anthers 4-locular; pistillate flowers perianth parts 3, to 2 mm, oblong-lanceolate to linear, tip acute, stigmas 3 and erect, ovary ovoid, styles absent.

Fruit

Utricles dehiscing along a fissure encircling the whole fruit, 1.5-2 mm, larger than or equal to perianth, ellipsoid-ovoid, greenish white to brown, wrinkled especially near tip;

seed approximately 1 mm, lenticular, reddish brown, smooth, shiny.