Page authors: Don Knoke, David Giblin
Amaranthus retroflexus
redroot pigweed, rough pigweed

Distribution: In scattered locations throughout Washington, but more commonly east of the Cascade crest; widely distributed throughout much of North America.

Habitat: Disturbed areas.

Flowers: July-October

Origin: Introduced from eastern and central North America

Growth Duration: Annual

Conservation Status: Not of concern


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


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 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.


1-seeded capsule.

Accepted Name:
Amaranthus retroflexus L.
Publication: Sp. Pl. 2: 991. 1753. 1753.

Synonyms & Misapplications:
Amaranthus retroflexus L. var. salicifolius I.M. Johnst.
Additional Resources:

PNW Herbaria: Specimen records of Amaranthus retroflexus in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Amaranthus retroflexus checklist entry.

E-Flora BC: Amaranthus retroflexus atlas page.

CalPhotos: Amaranthus retroflexus photos.

USDA Plants: Amaranthus retroflexus information.

16 photographs:
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