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

Lactuca biennis (Moench) Fernald
tall blue lettuce
Asteraceae (Aster family)

Introduction to Vascular Plants

© Jamie Fenneman  Email the photographer   (Photo ID #11531)

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Distribution of Lactuca biennis
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Species Information

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Annual or biennial herb from a taproot; stems erect, branched above, usually solitary, glabrous, exuding milky juice when broken, 0.6-2.5 m tall.
Basal leaves lacking; stem leaves alternate, pinnately cut or toothed, 10-40 cm long, 4-20 cm wide, sometimes hairy along the main veins, the upper ones with ear-like flanges at the base, clasping.
Heads with strap-shaped flowers, numerous in a narrow, elongate inflorescence; involucres 9-14 mm tall; involucral bracts lanceolate, graduated, often purplish at the tip, glabrous; ray flowers bluish to white, sometimes yellow, 13-34.
Achenes thin-edged, prominently nerved, beakless or shortly stout-beaked less than 1/2 the length of the body, 4-5.5 mm long; pappus brownish.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Moist ditches, meadows and forest openings in the lowland, steppe and montane zones; frequent throughout most of BC; E to NF and S to NC, CO and CA.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Lactuca biennis

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) 44 244 555
Slope Gradient (%) 0 10 76
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
45 220 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
2 3 4
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: CWH(26), SBS(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.

Synonyms and Alternate Names

Lactuca spicata auct. non (Lam.) Hitchc.
Lactuca spicata var. integrifolia (Torr. & A. Gray) Britton
Mulgedium spicatum auct. non (Lam.) Small
Mulgedium spicatum var. integrifolium (Torr. & A. Gray) Small

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References