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Montana Field Guides

Latah Tule Pea - Lathyrus bijugatus

Species of Concern
Native Species

Global Rank: G4
State Rank: S2S3
(see State Rank Reason below)
State Threat Score: No Known Threats
CCVI: Less Vulnerable

Agency Status


External Links

State Rank Reason (see State Rank above)
Rare and peripheral in Montana. Currently documented from three, widely scattered sites in the valleys-lower mountains of northwest Montana.
  • Details on Status Ranking and Review
    Latah Tule Pea (Lathyrus bijugatus) Conservation Status Review
    Review Date = 06/07/2012
    View State Conservation Rank Criteria
    Population Size

    Score1 - Moderate: Generally 10,000-100,000 individuals.

    Range Extent

    Score1 - Peripheral, Disjunct or Sporadic Distribution in MT: Widespread species that is peripheral, disjunct or sporadically distributed within MT such that it occurs in <5% of the state (<7,500 sq. miles or the combined area of Beaverhead and Ravalli Counties) or is restricted to 4-5 sub-basins.

    Area of Occupancy

    Score3 - Very Low: Generally occurring in 3 or fewer Subwatersheds (6th Code HUC’s).

    CommentAdditional surveys would likey find other locations. 1 occurrence is only known from an historical collection with imprecise locality data.

    Environmental Specificity

    Score1 - Moderate: Species is restricted to a specific habitat that is more widely distributed or to several restricted habitats and is typically dependent upon relatively unaltered, good-quality habitat (C Values of 5-7).


    Score0-2 - Stable to Moderate Declines:


    Score0-2 - Low to High Threat Levels.

    Intrinsic Vulnerability

    Score1 - Moderate Vulnerability: Specific biological attributes, unusual life history characteristics or limited reproductive potential makes the species susceptible to extirpation from stochastic events or other adverse impacts to its habitat and slow to recover.

    Raw Conservation Status Score

    Score 7 to 11 total points scored out of a possible 19.

General Description
Latah Tule Pea is an herbaceous perennial with erect stems that stand 1-3 dm tall and arise from slender rhizomes. The alternate leaves have 2-4 paired, strap-shaped to oblong leaflets that are 2-15 cm long and a bristle instead of a tendril on the tip. Each leaf has a pair of narrow, leaf-like wings, or stipules at the point of stem attachment. Foliage is glabrous to sparsely short-hairy. 2-3 pink to light blue, pea-like flowers, 10-13 mm long, are borne on ascending stalks in the axils of the upper leaves. The upper petal is reflexed upward and equal in length to the wing petals but longer than the keel petals. The calyx is 6-8 mm long and has 5 pointed lobes. The fruit is a flattened, elongate-elliptic pod that is 3-4 cm long with 7-12 seeds.

Flowering in June.

Diagnostic Characteristics
Vicia americana and Lathyrus ochroleucus have a tendril instead of a bristle on the leaf tip.

Species Range
Montana Range Range Descriptions


Range Comments
Known from Flathead and Lincoln counties. Endemic to ID, adjacent WA and MT (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 14

(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 ponderosa pine and western larch forests in the valley and lower montane 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

The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus appositus, Bombus fervidus, Bombus flavifrons, Bombus sitkensis, and Bombus occidentalis (Thorp et al. 1983, Colla and Dumesh 2010, Koch et al. 2012).

Threats or Limiting Factors
Threat impact not assigned because threats are not documented. (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.
  • 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.
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Citation for data on this website:
Latah Tule Pea — Lathyrus bijugatus.  Montana Field Guide.  .  Retrieved on , from