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Montana Field Guide

Montana Field Guides

Western Joepye-weed - Ageratina occidentalis
Other Names:  Western Boneset, Eupatorium occidentale

Species of Concern
Native Species

Global Rank: G4
State Rank: S2
(see State Rank Reason below)
State Threat Score: Unknown
CCVI: Less Vulnerable

Agency Status
USFS: Sensitive - Known in Forests (BRT)
Sensitive - Suspected in Forests (BD, LOLO)



External Links

State Rank Reason (see State Rank above)
This peripheral species in Montana is known from a handful of small to large populations in the extreme western part of the state. Minor impacts associated with a rock quarry at one location and rock climbing at another site are possible. Otherwise, few threats have been documented for the species in Montana.
General Description
Western Joepye-weed is a rhizomatous perennial herb with clustered stems that are often woody at the base and 15-70 cm tall. The alternate leaves are triangular or ovate in outline and 2-7 cm long with toothed margins. The lower leaves are reduced and early deciduous. The lower leaf surfaces have small, unstalked glands. The flowering heads are borne in an open, branched inflorescence. The involucral bracts are 3-5 mm long and mostly equal in length. The heads lack ray flowers, and there are 9-21 purple or pink disk flowers in each head. The top of the achene bears a tuft of numerous fine bristles.

Flowering in August.

Diagnostic Characteristics
This species could be confused with Brickellia grandiflorra or Saussurea americana but both of these have involucral bracts in many rows of different lengths.

Species Range
Montana Range Range Descriptions


Range Comments
WA to MT south to CA, NV, UT. Collected in Mineral and Ravalli counties (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

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)

Rocky outcrops and slopes in the montane and lower subalpine zones.
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habitat Model available.

To learn how these Models were created see

Ecological Systems Associated with this Species

Threats or Limiting Factors
Threats to Montana’s populations of Western Joepye-weed are assigned as unknown because of undocumented existing and potential impacts (MTNHP Threat Assessment 2021).

  • Literature Cited AboveLegend:   View Online Publication
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 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.
  • Web Search Engines for Articles on "Western Joepye-weed"
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Citation for data on this website:
Western Joepye-weed — Ageratina occidentalis.  Montana Field Guide.  .  Retrieved on , from