Symphyotrichum spathulatum var. intermedium (Lindl.) G.L. Nesom (A. Gray) G.L. Nesom
western mountain aster
Asteraceae (Aster family)

Introduction to Vascular Plants


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E-Flora BC Static Map

Distribution of Symphyotrichum spathulatum var. intermedium
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Species Information

Perennial herb from a fibrous-rooted, creeping rhizome; stems ascending to erect, branched above, glabrous to slightly hairy; 0.2-1.0 m tall.
Basal leaves soon deciduous; stem leaves oblanceolate and stalked below, linear or lanceolate and unstalked above, 3-15 cm long, 3-13 mm wide, mostly 7-10 times as long as wide, mostly glabrous, entire.
Heads with ray and disk flowers, solitary to many in an open, round-topped inflorescence; involucres 5-7 mm tall; involucral bracts scarcely to evidently graduated, linear to linear-oblong, abruptly sharp-pointed, rarely obtuse, glabrous, margins fringed with small hairs, often green to the base, infrequently minutely purple-tipped; ray flowers 20-50, blue to violet or purple, 6-15 mm long; disk flowers yellow.
Achenes obscurely nerved, hairy; pappus whitish.
Two fairly distinct varieties occur in our region and may be separated as follows:

1. Heads solitary or several in a sparsely leafy, few-branched inflorescence; leaves linear.......................... var. occidentalis

1. Heads numerous in a leafy, much-branched inflorescence; leaves lanceolate........................... var. intermedius A. Gray

SourceThe Illustrated Flora of British Columbia


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Ecological Framework for Symphyotrichum spathulatum var. intermedium

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)
1698 1698 1698
Slope Gradient (%)
4 4 4

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

324 325 325
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
7 7 7
Modal Nutrient Regime
# of field plots
 species was recorded in:
Modal BEC Zone Class

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


Habitat and Range

Mesic meadows and open forests in the lowland and montane zones; both varieties frequent in S BC east of the Coast-Cascade Mountains and S of 55degreeN, var. occidentalis also infrequent on S Vancouver Island and the mainland coast; N to NT, and S to CO and CA.

SourceThe Illustrated Flora of British Columbia


Synonyms and Alternate Names:
Aster occidentalis var. intermedius A. Gray
Aster occidentalis var. occidentalis