Distribution: Occurring chiefly east of the Cascades crest; Alaska to California, east across North America to the Atlantic Coast.
Habitat: Roadsides, fields, wastelots, and other disturbed sites, often where moist.
Growth Duration: Annual
Conservation Status: Not of concern
Monoecious, coarse annual from a few decimeters to several meters tall with short, stiff hairs above.
Leaves opposite, petiolate, ovate or sub-orbicular, serrate, palmately 3- to 5-lobed, or without lobes in small plants, the blade 2 dm. long or more, rough on both sides.
Staminate heads small, numerous, short-pedunculate, in an elongate, bractless, spike-like inflorescence, the involucres 3-nerved; pistillate heads borne below, in the leaf axils, the involucres 5-10 mm. long in fruit, several-ribbed, each bearing a short spine at the summit.