Page author: Don Knoke
Sonchus asper
prickly sow thistle, spiny leaf sow thistle
WTU specimens
Other herbaria

Distribution: Cosmopolitan; common in the Pacific Northwest

Habitat: Disturbed areas, roadsides, gardens

Flowers: July - October

Origin: Introduced from Europe

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.

Identification Notes:

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..

Accepted Name:
Sonchus asper (L.) Hill
Publication: Herb. Brit. 1: 47. 1769. 1769.

Synonyms & Misapplications:
Sonchus oleraceus L. var. asper L.
ssp. asper – prickly sow thistle, spiny leaf sow thistle
Additional Resources:

PNW Herbaria: Specimen records of Sonchus asper in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Sonchus asper checklist entry.

E-Flora BC: Sonchus asper atlas page.

CalPhotos: Sonchus asper photos.

USDA Plants: Sonchus asper information.

43 photographs:
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