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

Tetradymia canescens DC.
grey horsebrush (spineless horsebrush)
Asteraceae (Aster family)

Introduction to Vascular Plants

© David Shackleton  Email the photographer   (Photo ID #79619)

E-Flora BC Static Map
Distribution of Tetradymia canescens
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Species Information

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Evergreen shrub; stems much branched, unevenly woolly-hairy, 10-80 cm tall.
Alternate, entire, white woolly-hairy; primary leaves linear spoon-shaped, 1-3 cm long, 1-4 mm wide; secondary leaves similar but shorter and narrower.
Heads discoid, 3- to 8-headed clusters at the tips of branches; involucres 7-10 mm tall; involucral bracts oblong to egg-shaped or lanceolate, 4 or 5, subequal, white woolly-hairy; ray flowers lacking; disk flowers creamy to bright yellow.
Achenes densely hairy, 3-5 mm long; pappus of numerous white to tawny bristles.

Source: The Illustrated Flora of British Columbia

USDA Species Characteristics

Flower Colour:
Blooming Period:
Late Summer
Fruit/Seed characteristics:
Colour: Brown
Present from Fall to Winter
Source:  The USDA

Habitat / Range

Dry grasslands and shrublands in the steppe and lower montane zones; frequent in SC BC; E to MT and S to NM and CA.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Tetradymia canescens

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) 330 672 1265
Slope Gradient (%) 0 18 65
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
10 192 351
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
0 3 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(21), IDF(3), PP(8)


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

Tetradymia canescens var. inermis (Rydb.) Payson

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References