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Montana Field Guide

Montana Field Guides

Columbia Onion - Allium columbianum

Species of Concern
Native Species

Global Rank: G3
State Rank: S1
(see State Rank Reason below)
State Threat Score: Medium
CCVI: Highly Vulnerable

Agency Status
USFS: Sensitive - Known in Forests (BD)


External Links

State Rank Reason (see State Rank above)
Known from one occurrence in Camas Prairie. Part of this occurrence has been replaced by a gravelpit. Nearly all suitable habitat in the area has been converted to agriculture. Invasive weeds may also negatively impact the remaining habitat and threaten the population. Survey and monitoring data are needed.
  • Details on Status Ranking and Review
    Columbia Onion (Allium columbianum) Conservation Status Review
    Review Date = 11/07/2012
    View State Conservation Rank Criteria
    Population Size

    Score3 - Vey Small: Generally <2,000 individuals.

    CommentPopulation size is apparently very small, though exact numbers are uncertain.

    Range Extent

    Score3 - Local Endemic or Very Small Montana Range: Generally restricted to an area <10,000 sq. miles (equivalent to the combined area of Phillips and Valley Counties) or <6 Sub-basins (4th code watersheds) Range-wide OR limited to one Sub-basin in Montana

    Area of Occupancy

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

    Environmental Specificity

    Score1-2 - Moderate to High.


    Score2-3 - Moderate to Severe Declines:

    CommentDeclines have taken place as part of one population was impacted by a gravelpit, though the severity of the decline is uncertain.


    Score2-3 - High to Very High.

    CommentDevelopment (gravelpit) and invasive species are the primary threats to the species.

    Intrinsic Vulnerability

    Score0-1 - Low to Moderate Vulnerability.

    Raw Conservation Status Score

    Score 14 to 18 total points scored out of a possible 19.

General Description
Bulbs globose, solitary or clustered; outer coat membranous, lacking reticulations. Scapes terete, 20–40 cm. Leaves 2, falcate, flat, 3–12 mm wide, persistent. Umbel hemispheric to globose with 20 to 50 flowers; pedicels 6–10 mm long; bracts 3, ovate, apiculate. Flowers rose to magenta; tepals 6–9 mm long; ovary with 6 low, rounded crests; stamens ca. as long as the tepals. Seed surface smooth (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Flowering in June.

Diagnostic Characteristics
The broad sickle-shaped leaves and swollen stem beneath the inflorescence distinguish it from other species of Allium in our area.

Species Range
Montana Range Range Descriptions


Range Comments
Regional endemic from eastern WA, northern ID and west-central MT.

Observations in Montana Natural Heritage Program Database
Number of Observations: 13

(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)

Moist swales and along vernal ponds and streams in the valleys.
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 flavifrons, Bombus huntii, Bombus melanopygus, Bombus sylvicola, Bombus occidentalis, and Bombus bohemicus (Macior 1974, Thorp et al. 1983, Colla and Dumesh 2010, Koch et al. 2012, Miller-Struttmann and Galen 2014, Williams et al. 2014).

Threats or Limiting Factors
Reported threats to Montana’s populations of Columbia Onion are those that impact its habitat fragments in swales and along wetland margins (MTNHP Threat Assessment 2021). Nearly all of its historic suitable habitat has been converted to agricultural use, and populations remain along the edges of fields, next to roads, or vernally moist forest openings. Populations are exposed to road construction and maintenance, noxious weeds, and trampling by hikers, off-highway vehicles, and horses. Chemical herbicide may also impact plants or populations where noxious species have established. Information on the scope and severity of herbicide application is needed to assess its relative risk to populations.

  • 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.
    • Macior, L.M. 1974. Pollination ecology of the Front Range of the Colorado Rocky Mountains. Melanderia 15: 1-59.
    • Miller-Struttmann, N.E. and C. Galen. 2014. High-altitude multi-taskers: bumble bee food plant use broadens along an altitudinal productivity gradient. Oecologia 176:1033-1045.
    • 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.
    • Williams, P., R. Thorp, L. Richardson, and S. Colla. 2014. Bumble Bees of North America. Princeton, NJ: Princeton University Press. 208 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.
    • Rieseberg, L.H., P.M. Peterson, D.E. Soltis, and C.R. Annable. 1987. Genetic divergence and isozyme number variation among four varieties of Allium douglasii (Alliaceae). American Journal of Botany 74:1614-1624.
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Citation for data on this website:
Columbia Onion — Allium columbianum.  Montana Field Guide.  .  Retrieved on , from