General:
Perennial herb from a fibrous-rooted, creeping rhizome; stems ascending to erect, branched above, glabrous to slightly hairy; 0.2-1.0 m tall.

Leaves:
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.

Flowers:
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.

Fruits:
Achenes obscurely nerved, hairy; pappus whitish.

Notes:
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

Source:  The 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.

Illustration Source:  The Illustrated Flora of British Columbia

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