[Asters: The Genera Canadanthus, Eucephalus, Eurybia, Oreostemma and Symphyotrichum Found East of the Cascade Mountains of Oregon and Washington]

Larger Western Mountain Aster

Symphyotrichum spathulatum var. intermedium

Synonyms: Aster spathulatus var. intermedius, Aster occidentalis ssp. intermedius,  Aster occidentalis var. intermedius

Western Mountain Aster: Symphyotrichum spathulatum var. intermedium, Symphyotrichum spathulatum var. spathulatum (Synonyms: Aster occidentalis var. intermedius, Aster occidentalis var. spathulatum)

Western mountain aster as found in a roadside ditch along forest service road #3521, Wenatchee National Forest........August 13, 2009.

Characteristics:

Western aster is an erect perennial wildflower arising 20-100 cm from a creeping rhizome. The herbage is generally smooth or without hairs. The lower stem leaves are oblanceolate in shape and petiolate, and they tend to persist into flowering. They may have entire or serrate margins. The middle and upper leaves are narrower with entire margins and measure from 3-15 cm long and 3-15 mm wide. The leaves tend to be 7-20 times longer than they are wide.

The inflorescence is a corymb or cymose panicle of one to many flower heads about 2.5 cm wide. The involucre is 5-7 mm high with obtuse to acutely tipped bracts. The bracts are green and occasional purple margined. Individual bracts are narrowly linear or linear-oblong with short hairs along the margins. The 20-50 rays are about 6-15 mm long and blue, violet or purple in color.

Variety intermedius is much larger and more branched than variety occidentalis with more flower heads arranged in a leafy-bracteate inflorescence.

Habitat:

Western mountain aster may be found in mountain meadows. Variety intermedius may be found at lower elevations than variety occidentalis.

Range:

Western aster is found from British Columbia south through Washington and Oregon to California, and eastward to Idaho and Colorado.

Variety intermedius tends to be found in the eastern portion of the range of the species in eastern Washington and northern Idaho.

Flower head of Western Mountain Aster: Symphyotrichum spathulatum var. intermedium, Symphyotrichum spathulatum var. spathulatum (Synonyms: Aster occidentalis var. intermedius, Aster occidentalis var. spathulatum) - Inflorescence of Western Mountain Aster: Symphyotrichum spathulatum var. intermedium, Symphyotrichum spathulatum var. spathulatum (Synonyms: Aster occidentalis var. intermedius, Aster occidentalis var. spathulatum) - Involucral bracts of Western Mountain Aster: Symphyotrichum spathulatum var. intermedium, Symphyotrichum spathulatum var. spathulatum (Synonyms: Aster occidentalis var. intermedius, Aster occidentalis var. spathulatum)

Western mountain aster as found in a roadside ditch along forest service road #3521, Wenatchee National Forest.........August 13, 2009.

Western Mountain Aster: Symphyotrichum spathulatum var. intermedium, Symphyotrichum spathulatum var. spathulatum (Synonyms: Aster occidentalis var. intermedius, Aster occidentalis var. spathulatum)

Western mountain aster as found in a vernally moist area along Forest Service Road 16 in Summit Prairie, Malheur National Forest.........August 2, 2011.

Western aster as found at the mouth of the Deschutes River...........September 3, 2000. Note the narrow bracts tapering gradually to a fairly sharp point.

- - Western Mountain Aster

Close-ups of a stem leaf, the upper stem and inflorescence and a flower head of western mountain aster as found along Road K1000 on the southeastern slopes of Mt. Adams.........June 17, 2006. Note the narrow bracts tapering gradually to a fairly sharp point.
Paul Slichter