Distribution: Occurring on both sides of the Cascades crest in Washington, but more common west of the crest; Alaska to California, east to the Atlantic Coast.
Habitat: Forest edge, balds, prairies, roadsides, ditches, wastelots, and other disturbed open areas at low elevations.
Origin: Introduced from Europe
Growth Duration: Annual
Conservation Status: Not of concern
Glabrous annual 1-10 dm. tall, with milky juice.
Leaves quite prickly margined, usually pinnatifid, but frequently obovate and lobeless, with rounded (not acute) auricles, progressively reduced and less divided upward.
Heads several in a somewhat flat-topped inflorescence, 1.5-2.5 cm. wide; fruiting involucre 9-14 mm. high; corollas all ligulate, yellow.
Achenes with 3 prominent longitudinal ribs on each face, but not wrinkled.
The similar S. oleraceus has leaf margins that are weakly prickly, the lobes on the pinnatifid leaves point backward, the auricles are sharply acute, and the achenes are wrinkled..