E-Flora BC: Electronic Atlas of the Flora of British Columbia

Sonchus oleraceus L.
common sow-thistle (annual sow-thistle; common sowthistle)
Asteraceae (Aster family)

Introduction to Vascular Plants

© Bryan Kelly-McArthur  Email the photographer   (Photo ID #76927)

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Distribution of Sonchus oleraceus
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Species Information

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Annual herbs from a short taproot; stems erect, solitary, few-branched above, glabrous, hollow, exuding milky juice when broken, 0.1-1 m tall.
Basal leaves lacking; stem leaves alternate, weakly or scarcely prickly-margined, lowermost stalked, backward-swept pinnately cut to occasionally merely toothed, 6-30 cm long, 1-15 cm wide, uppermost lobed with sharply pointed ear-lke lobes.
Heads with strap-shaped flowers, several on sometimes glandular stalks in an open, flat- or round-topped inflorescence, relatively small, commonly 1.5-2.3 cm wide in flower; involucres 9-14 mm tall; involucral bracts lanceolate, tapering to a slender tip at the apex, glabrous except for some spreading, gland-tipped hairs; ray flowers yellow.
Achenes 2.5-3 mm long, with 3-5 evident to rather obscure longitudinal ribs on each face, cross-wrinkled; pappus of white hairlike bristles.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Mesic to dry roadsides, disturbed areas and gardens in the lowland and lower montane zone; frequent on S Vancouver Island, infrequent elsewhere on the coast; introduced from Europe.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Sonchus oleraceus

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class




Elevation (metres) 283 657 1097
Slope Gradient (%) 0 27 50
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
70 169 210
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
1 2 5
Modal Nutrient Regime
Number of field plots
 species was recorded in:
Modal BEC Zone Class
All BEC Zones (# of stations/zone) species was recorded in: BG(2), IDF(3), PP(1)


The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Taxonomic and Nomenclatural Links

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General References