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Montana Field Guide

Montana Field Guides

Antelope Bitterbrush - Purshia tridentata

Native Species

Global Rank: G4G5
State Rank: S4
(see State Rank Reason below)

Agency Status
MNPS Threat Rank:
C-value: 4

External Links

State Rank Reason (see State Rank above)
See rank details.
  • Details on Status Ranking and Review
    Antelope Bitterbrush (Purshia tridentata) Conservation Status Review
    Review Date = 10/31/2012
    View State Conservation Rank Criteria
    Population Size

    Score0 - Large: Generally >100,000 individuals.

    Range Extent

    Score0 - Widespread species within Montana (occurs in 5% or more of the state or generally occurring in 6 or more sub-basins.) as well as outside of Montana.

    Area of Occupancy

    Score0 - High: Occurs in >25 Subwatersheds (6th Code HUC’s).

    Environmental Specificity

    Score0 - Low: Species is a generalist that occurs in a variety of habitats and/or is tolerant of disturbed or degraded habitats (C -Values of 1-4).


    Score1 - Minor Declines: Species has experienced declines of 10-30% in population size, range extent and/or occupied area in the recent past (approximately 30 years).

    CommentMinor declines are likely from habitat conversion and alteration.


    Score1 - Medium: 11-30% of the populations are being negatively impacted or are likely to be impacted by one or more activities or agents, which are expected to result in decreased populations and/or habitat quality and/or quantity.

    CommentVarious impacts and threats exist across the species' range in Montana though none are severe in magnitude.

    Intrinsic Vulnerability

    Score0-1 - Low to Moderate Vulnerability.

    Raw Conservation Status Score

    Score 2 to 4 total points scored out of a possible 19.

General Description
Intricately branched shrub to 2 m. Stems rigid, erect to ascending; bark brown, tomentose, becoming gray. Leaves fascicled on tips of short shoots, simple, sessile, fan-shaped, 7–18 mm long, shallowly 3-lobed at the tip, tomentose, sparsely so above, dense beneath, margins inrolled. Inflorescence of solitary, sessile flowers from tips of short shoots. Flowers perfect, perigynous; hypanthium obconic, tomentose, glandular, 4–6 mm long; sepals 5, ovate, 2–3 mm long; petals 5, clawed, yellow, 4–7 mm long; stamens ca. 25; pistil 1. Fruit a pubescent, ellipsoid achene, 9–14 mm long, partly enclosed in the hypanthium; style ca. 1 mm long. Stony or sandy soil of grasslands, steppe, open ponderosa-pine forest; valleys, montane(Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Species Range

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

Observations in Montana Natural Heritage Program Database
Number of Observations: 182

(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)

Stony or sandy soil of grasslands, steppe, open ponderosa-pine forest; valleys, montane

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Citation for data on this website:
Antelope Bitterbrush — Purshia tridentata.  Montana Field Guide.  .  Retrieved on , from