Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across North America to the Atlantic Coast.
Habitat: Roadsides, fields, pastures, wastelots, and other dry, disturbed, open areas at low elevations.
Origin: Introduced from eastern North America
Conservation Status: Not of concern
Monoecious, branching annual, variously hairy, 1-10 dm tall.
Leaves opposite below and alternate above, usually bi-pinnatifid, ovate or elliptic in outline, 3-10 cm. long, the lower and middle ones petiolate.
Staminate heads small, numerous, short-pedunculate, in an elongate, bractless, spike-like inflorescence; pistillate heads borne below, in the axils of bracts; fruiting involucre a short-beaked bur, 3-5 mm. long, with several short, sharp spines.