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Montana Field Guide

Montana Field Guides

Slender Fleabane - Erigeron tener

Species of Concern
Native Species

Global Rank: G4
State Rank: S2?
(see State Rank Reason below)
State Threat Score: No Known Threats

Agency Status


External Links

State Rank Reason (see State Rank above)
Rare in Montana, where it is currently known from a single locality in the southwest corner of the state. Current population levels and trends are unknown.
General Description
Slender Fleabane is a perennial with 1-few stems that are 3-15 cm tall, arising from a taproot and woody rootcrown. Foliage is covered by short hairs. The basal leaves have a pointed leaf blade 7-25 mm long tapering at the base to the leaf stalk. Stem leaves are linear and few. The daisy-like, flowering heads are 1-3 on the stem. Involucral bracts are 3.5 mm long, finely glandular, and usually with short, spreading hairs. The 15-40 rays are blue or sometimes purple, 4-8 mm long and 1-1.7 mm wide. The achenes have 15-30 inner bristles about as long as the disk corollas, and outer bristles are obscure or wanting.

Flowering in late July - early August.

Diagnostic Characteristics
A combination of the woody rootcrown, single-veined basal leaves, reduced stem leaves, absence of spreading stem hairs, blue rays, and leaf shape distinguish it from most western Erigeron in our area including E. tweedyi and E. cespitosus. A hand lens or microscope and technical key are needed for positive identification.

Species Range
Montana Range Range Descriptions


Range Comments
Beaverhead County. OR to MT south to CA, AZ and WY (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 3

(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)

Open limestone slopes in the upper montane zone.
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habitat Model available.

To learn how these Models were created see

The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus bifarius, Bombus centralis, Bombus fervidus, Bombus flavifrons, Bombus huntii, Bombus melanopygus, Bombus mixtus, Bombus rufocinctus, Bombus occidentalis, and Bombus insularis (Thorp et al. 1983, Wilson et al. 2010, Colla and Dumesh 2010, Koch et al. 2012).

Threats or Limiting Factors
Threat impact not assigned because threats are not known (MTNHP Threat Assessment 2021).

  • Literature Cited AboveLegend:   View Online Publication
    • 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.
    • 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.
    • Wilson, J.S., L.E. Wilson, L.D. Loftis, and T. Griswold. 2010. The montane bee fauna of north central Washington, USA, with floral associations. Western North American Naturalist 70(2): 198-207.
  • 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.
    • Lesica, P., P. Husby, and S. V. Cooper. 1998. Noteworthy collections: Montana. Madrono 45:328-330.
  • Web Search Engines for Articles on "Slender Fleabane"
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Citation for data on this website:
Slender Fleabane — Erigeron tener.  Montana Field Guide.  .  Retrieved on , from