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Montana Field Guide

Montana Field Guides

Western Mountain Aster - Symphyotrichum spathulatum
Other Names:  Aster spathulatus, Aster occidentalis

Native Species

Global Rank: G5
State Rank: S5

Agency Status
MNPS Threat Rank:
C-value: 5

External Links

General Description
Rhizomatous perennial. Stems erect to ascending, 15–60 cm. Herbage glabrate. Leaves basal and cauline, petiolate below; blades linear to lanceolate, 3–12 cm long, entire; the upper sessile and narrower. Inflorescence open-paniculate with few heads; peduncles glabrate to densely strigose. Involucre campanulate, 6–9 mm high; phyllaries linear-oblanceolate, imbricate, green with white bases, glabrous to ciliate. Rays 15 to 40, blue or violet; ligules 7–15 mm long. Disk flowers 30 to 80, yellow becoming purple; corollas 4–8 mm long. Achenes cylindric, 2–4 mm long, hairy (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Our plants are variety spathulatum.

Species Range
Montana Range


Range Comments
BC, AB south to CA, UT and NM (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 498

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Wet meadows, thickets, fens, open forest; valleys to subalpine (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Fultz, J.E. 2005. Effects of shelterwood management on flower-visiting insects and their floral resources. M.Sc. Thesis. Bozeman, MT: Montana State University. 163 p.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Zapatka, T.P. 1963. Some results of two limited hunting seasons on hen Pheasants in north central Montana. M.Sc. Thesis. Bozeman, Montana: Montana State University. 26 p.
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Citation for data on this website:
Western Mountain Aster — Symphyotrichum spathulatum.  Montana Field Guide.  .  Retrieved on , from