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

Introduction to Vascular Plants


© Bryan Kelly-McArthur     (Photo ID #76927)


E-Flora BC Static Map

Distribution of Sonchus oleraceus
Click here to view the full interactive map and legend

Species Information

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.

SourceThe Illustrated Flora of British Columbia


If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.


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)
657 283 1097
Slope Gradient (%)
27 0 50

Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]

169 70 210
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
2 1 5
Modal Nutrient Regime
# 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)

Habitat and 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.

SourceThe Illustrated Flora of British Columbia