Distribution: Occurring on both sides of the Cascades crest in Washington, but more common west of the crest; Alaska to California, east across North America to the Atlantic Coast.
Habitat: Forest edge, balds, prairies, roadsides, ditches, wastelots, and other disturbed open areas at low elevations.
Flowers: June-October
Origin: Introduced from Europe
Growth Duration: Annual
Conservation Status: Not of concern
Pollination: Flies, butterflies
Mostly glabrous annual with a short taproot, 1-10 dm. tall, the juice milky.
Lowermost leaves ovate and petiolate, the others pinnatifid, with backward-pointing segments, or occasionally merely toothed, 6-30 cm. long and 1-15 cm. wide, the margins weakly prickly; all leaves with prominent, pointed auricles; leaves progressively less-divided upwards and somewhat reduced.
Heads several in a flat-topped inflorescence, relatively small, usually only 1.5-2.5 cm. wide; involucre 9-14 mm. high, the bracts of uneven lengths, some quite short; corollas all ligulate and perfect, yellow; pappus of numerous, white, capillary bristles.
Achenes 2.5-3 mm. long, with transverse wrinkles.
PNW Herbaria: Specimen records of Sonchus oleraceus in the Consortium of Pacific Northwest Herbaria database
WA Flora Checklist: Sonchus oleraceus checklist entry
OregonFlora: Sonchus oleraceus information
E-Flora BC: Sonchus oleraceus atlas page
CalPhotos: Sonchus oleraceus photos