[Asters: The Genera Canadanthus, Eucephalus, Eurybia, Oreostemma, and Symphyotrichum in Mt. Adams Country]
Western Mountain Aster, Western Aster
Symphyotrichum spathulatum
Synonyms: Aster occidentalis, Aster occidentalis var. fremontii, Aster occidentalis var. intermedius, Aster occidentalis var. occidentalis, Aster spathulatus, Aster spathulatus var. spathulatus, Aster vallicola, Symphyotrichum spathulatum var. intermedium, Symphyotrichum spathulatum var. spathulatum, Symphyotrichum spathulatum var. yosemitanum
The photo above shows a close-up of the flower head of western
mountain aster as found in a vernally moist area along Road K1000 to the east
of the Mount Adams Highway.........June 17, 2006.
The photo at
right illustrates the mid to upper stem leaves of western aster as found in prairie alongside Lakeside Road in Conboy Lake National Wildlife Refuge.........August 10, 2007. Note the narrow
leaves which taper gradually to a point. They also are sessile to short-petiolate.
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 aster may be found in mountain meadows and in riparian
areas along streams and rivers. Variety intermedius may be found
at lower elevations than variety occidentalis.
Range:
Western mountain aster is found from British Columbia south
through Washington and Oregon to California, and eastward to Idaho and Colorado.
- 
The photo at left shows the upper stem and inflorescence
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. The photo at right shows a portion of the inflorescence of western mountain aster as seenin wetlands along the Willard Springs Trail at Conboy Lake NWR.........September 17, 2017.
One of the larger (and wider) stem leaves of
western mountain aster as found along Road K1000 on the southeastern slopes
of Mt. Adams.........June 17, 2006.
- 
- 
- 
The photos above show various views of western mountain aster as seen in prairie alongside Lakeside Road in Conboy Lake NWR..........August 10, 2007.
- 
- 
The 3 photos above show close-ups of western mountain aster as seen in Swampy Meadows on the western slopes of Mt. Adams........September 6, 2008.
- 
Western mountain aster as seen in wetlands at Willard Springs, Conboy Lake National Wildlife Refuge......October 23, 2023.
Western mountain aster as seen in wetlands at Willard Springs, Conboy Lake National Wildlife Refuge.......August 26, 2018. This is former var. intermedius with a more branched inflorescence, more flower heads and narrower stem leaves.
Paul Slichter
