western mountain-ash
Rosaceae (Rose family)
Introduction to Vascular Plants
Map
Distribution of Sorbus scopulina var. scopulina
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Species Information
General:
Medium to tall shrub, 1-5 m tall; stems several, erect to spreading, freely branched, reddish-brown to yellowish; winter buds and young growth sticky, somewhat white- or grey-hairy.
Leaves:
Alternate, deciduous, pinnately compound; leaflets (7) 9 to 13, oblong-lanceolate to narrowly elliptic, 2-8 cm long, usually short-tapering to a sharp-pointed tip, smooth, finely saw-toothed almost to the base.
Flowers:
Inflorescence a flat-topped to somewhat rounded, branched cluster of numerous (70 to 200 or more) small flowers, the branches more or less white-hairy; corollas white to cream, the petals 5, oval, 4-6 mm long; calyces white-hairy, 5-lobed, the lobes triangular; ovaries inferior; stamens 15-20.
Fruits:
Berry-like pomes (like miniature apples), nearly globe-shaped, 7-10 mm long, orange to scarlet, not glaucous, 2- to 5-chambered; seeds 1 or 2 per chamber.
Notes:
Two varieties occur in BC:
1. Leaflets often 13; stipules usually shed before end of blooming; plants from E of Coast-Cascade Mountains................ var. scopulina
1. Leaflets rarely more than 11; stipules persistent until after blooming; plants from W slope of Cascade Mountains..................... var. cascadensis (G.N Jones) C.L. Hitchc.
Ecology
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 |
||
|
Avg |
Min |
Max |
|
| Elevation
(metres) |
1514 | 1100 | 1731 |
| Slope
Gradient (%) |
29 | 5 | 52 |
|
Aspect (degrees) |
124 | 110 | 150 |
| Soil
Moisture Regime (SMR) [0 - very xeric; 4 - mesic; 8 - hydric] |
3 | 2 | 4 |
| Modal
Nutrient Regime
Class |
C | ||
| #
of field plots species was recorded in: |
3 | ||
| Modal
BEC Zone Class |
ESSF | ||
|
All BEC Zones (# of stations/zone) species was recorded in |
ESSF(3) | ||
|
Source:
Klinkenberg 2013
|
|||
Habitat and Range
Mesic to moist glades, streambanks, forest edges and open forests in the montane and subalpine zones; frequent throughout BC, except rare W of Coast-Cascade Mountains; N to AK, E to AB and S to ND, WY, NM and N CA.Status Information
Taxonomic Keys
1. Plants becoming trees over 5 m tall; leaflets usually more than 13, winter buds covered with long soft-hairy grey hairs; styles 2 or 3...........................S. aucuparia
1. Plants shrubby, usually less than 5 m tall; leaflets rarely as many as 13, winter buds not covered with long soft grey hairs; styles 3 to 5. 2. Winter buds rusty-hairy; calyces smooth on outside; leaflets blunt or rounded at the tip, toothed for not more than 3/4 of their length; styles 4 or 5, fruit red, glaucous...............S. sitchensis 2. Winter buds sticky, sparsely white-hairy; calyces hairy on outside; leaflets sharp-pointed at tip, toothed for most of their length; styles 3 or 4; fruit orange, not glaucous................S. scopulina Source: Illustrated Flora of British Columbia |