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Montana Field Guide

Montana Field Guides

Boreal Aster - Symphyotrichum boreale
Other Names:  Aster borealis, Aster junciformis

Native Species

Global Rank: G5
State Rank: S4
C-value: 7

Agency Status


External Links

General Description
Northern bog aster grows from very slender underground runners less than 1/16" thick. The very slender stems, about 1/8" thick, grow from 6 inches to 3 feet tall and are hairless in the lower half but have lines of hairs in the upper half. The stem leaves are long and narrow with a long pointed tip and a base that is rounded to slightly clasping the stem. The rough margins are inrolled and may have a few scattered teeth but usually have no teeth at all. The main vein on the underside of the leaf is sometimes hairy. The lower leaves have often withered and fallen off by the time the plant flowers. There are up to 20 branches at the top of the plant with one flower head at the end of each branch. Small plants usually only have one flower at the top. The small leaf bracts around the bottom of the flower head are overlapping and held tight to the head. There are 20-30 white to pale rose or bluish ray flowers, 1/2 to 3/4" in length, around a yellow disk which turns purplish brown with age. The flattened fruits have one rib on each side and are sparsely hairy.

Species Range
Montana Range Range Descriptions


Range Comments
A northern species that ranges south to New Jersey, West Virginia, Illinois, Iowa, Colorado, Idaho, and Washington.

Observations in Montana Natural Heritage Program Database
Number of Observations: 24

(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, organic, often calcareous soil of fens, wet meadows, thickets; valleys, montane (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus vagans, Bombus bifarius, Bombus borealis, Bombus centralis, Bombus fervidus, Bombus flavifrons, Bombus huntii, Bombus mixtus, Bombus rufocinctus, Bombus sylvicola, Bombus ternarius, Bombus terricola, Bombus sitkensis, Bombus pensylvanicus, Bombus griseocollis, Bombus impatiens, Bombus insularis, Bombus suckleyi, Bombus bohemicus, and Bombus kirbiellus (Plath 1934, Heinrich 1976, Thorp et al. 1983, Colla and Dumesh 2010, Colla et al. 2011, Koch et al. 2012, Williams et al. 2014, Tripoldi and Szalanski 2015).

  • Literature Cited AboveLegend:   View Online Publication
    • Colla, S., L. Richardson, and P. Williams. 2011. Bumble bees of the eastern United States. Washington, DC: USDA Forest Service, Pollinator Partnership. 103 p.
    • Colla, S.R. and S. Dumesh. 2010. The bumble bees of southern Ontario: notes on natural history and distribution. Journal of the Entomological Society of Ontario 141:39-68.
    • Koch, J., J. Strange, and P. Williams. 2012. Bumble bees of the western United States. Washington, DC: USDA Forest Service, Pollinator Partnership. 143 p.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Plath, O.E. 1934. Bumblebees and their ways. New York, NY: Macmillan Company. 201 p.
    • Thorp, R.W., D.S. Horning, and L.L. Dunning. 1983. Bumble bees and cuckoo bumble bees of California (Hymenoptera: Apidae). Bulletin of the California Insect Survey 23:1-79.
    • Tripoldi, A.D. and A.L. Szalanski. 2015. The bumble bees (Hymenoptera: Apidae: Bombus) of Arkansas, fifty years later. Journal of Melittology 50: doi:
    • Williams, P., R. Thorp, L. Richardson, and S. Colla. 2014. Bumble Bees of North America. Princeton, NJ: Princeton University Press. 208 p.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2022. Manual of Montana Vascular Plants, Second Edition. Fort Worth, TX: BRIT Press. viii + 779 p.
    • Meier, G.A. 1997. The colonization of Montana roadsides by native and exotic plants. M.Sc. Thesis. Bozeman, MT: Montana State University. 45 p.
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Citation for data on this website:
Boreal Aster — Symphyotrichum boreale.  Montana Field Guide.  .  Retrieved on , from