Sorbus sitchensis M. Roem.
Sitka mountain-ash (western mountain ash)
Rosaceae (Rose family)

Introduction to Vascular Plants


© Virginia Skilton     (Photo ID #9046)


E-Flora BC Static Map

Distribution of Sorbus sitchensis
Click here to view the full interactive map and legend

Species Information

Medium to tall shrub, 1-4 m tall; stems several, erect to spreading, sparingly branched, greyish-red; winter buds and young growth not sticky, somewhat rusty-hairy.
Alternate, deciduous, pinnately compound; leaflets 7 to 11, oblong to oblong-egg-shaped, 2-7 cm long, rounded to blunt at the tip, smooth above, sometimes rusty-hairy below, rather coarsely saw-toothed for not more than 3/4 their length.
Inflorescence a half-rounded, branched cluster of numerous (15 to 80) small flowers, the branches often minutely rusty-hairy; corollas white to cream, the petals 5, oval, 4-6 mm long; calyces mostly smooth, 5-lobed, the lobes triangular; ovaries inferior; stamens 15-20.
Berry-like pomes (like miniature apples), nearly globe-shaped to ellipsoid, 8-10 mm long, red, glaucous, 2- to 5-chambered; seeds 1 or 2 per chamber.
Two sympatric varieties occur in BC:

1. Leaflets entire or toothed mostly above midlength................ var. grayi (Wenzig) C.L. Hitchc.

1. Leaflets toothed one-half to three-quarters their length................. var. sitchensis

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 Sorbus sitchensis

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)
1258 0 2500
Slope Gradient (%)
25 0 200

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

250 0 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
3 0 8
Modal Nutrient Regime
# of field plots
 species was recorded in:
Modal BEC Zone Class

All BEC Zones (# of stations/zone) species was recorded in

AT(7), BWBS(19), CDF(4), CMA(1), CWH(190), ESSF(1250), ICH(563), IDF(53), MH(229), MS(146), SBPS(3), SBS(204)

Habitat and Range

Mesic to moist open forests, forest edges, streambanks, rockslides, thickets and meadows in the montane to alpine zones; common throughout BC (except NE BC), especially southward; N to AK and YT, E to AB and S to ID, MT and N CA.

SourceThe Illustrated Flora of British Columbia


Synonyms and Alternate Names:
Sorbus sitchensis subsp. californica (Greene) Abrams