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

Lactuca canadensis L.
Canadian wild lettuce (Canada lettuce)
Asteraceae (Aster family)

Introduction to Vascular Plants
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Distribution of Lactuca canadensis
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Species Information

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General:
Annual or biennial herb from a taproot; stems erect, branched above, usually solitary, glabrous or sometimes coarsely stiff-hairy, exuding milky juice when broken, 0.3-2.5 m tall.
Leaves:
Basal leaves lacking; stem leaves alternate, entire or toothed to pinnate, 10-35 cm long, 1.5-12 cm wide, triangular-shaped or narrowed at the base.
Flowers:
Heads with strap-shaped flowers, numerous in a narrow, elongate inflorescence; involucres 10-15 mm tall; involucral bracts lanceolate, graduated in 4-5 series, often purplish at the tip, glabrous; ray flowers yellow, 13-22.
Fruits:
Achenes blackish, flat, median nerve on each face, 4.5-6.5 mm long including the slender beak which varies from 1/2 as long to as long as the body; pappus white.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Mesic to dry roadsides, fields and waste places in the lowland, steppe and montane zones; infrequent in extreme S BC; introduced from E North America.

Source: The Illustrated Flora of British Columbia

Ecology

Ecological Framework for Lactuca canadensis

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

Minimum

Average

Maximum

Elevation (metres) 716 743 771
Slope Gradient (%) 0 2 5
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
265 265 265
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
4 4 5
Modal Nutrient Regime
Class
Number of field plots
 species was recorded in:
2
Modal BEC Zone Class
SBS
All BEC Zones (# of stations/zone) species was recorded in: SBS(2)

Climate

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.

Synonyms and Alternate Names

Lactuca canadensis var. canadensis L.
Lactuca canadensis var. integrifolia (Bigelow) Torr. & Gray
Lactuca canadensis var. latifolia Kuntze
Lactuca canadensis var. longifolia (Michx.) Farw.
Lactuca canadensis var. obovata Wieg.
Lactuca canadensis var. typica Wieg.
Lactuca sagittifolia Ell.
Lactuca steelei Britt.

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References