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

Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across North America to the Atlantic Coast.

Habitat: Fields, roadsides, wastelots, and other disturbed areas.

Flowers: July-October

Origin: Introduced from eastern and central North America

Growth Duration: Annual

Conservation Status: Not of concern

Pollination: Wind

Description:
General:

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.

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

OregonFlora: Amaranthus retroflexus information

E-Flora BC: Amaranthus retroflexus atlas page

CalPhotos: Amaranthus retroflexus photos

16 photographs:
Group by