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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

Agency Status
MNPS Threat Rank:
C-value: 7

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 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: 25

(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 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

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Citation for data on this website:
Boreal Aster — Symphyotrichum boreale.  Montana Field Guide.  .  Retrieved on , from