Page authors: Don Knoke, David Giblin
Sonchus oleraceus
common sow-thistle

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.

Accepted Name:
Sonchus oleraceus L.
Publication: Sp. Pl. 2: 794. 1753.

Synonyms & Misapplications:
(none provided)
Additional Resources:

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.

USDA Plants: Sonchus oleraceus information.

33 photographs:
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