Search Field Guide
Advanced Search
MT Gov Logo
Montana Field Guide

Montana Field Guides

Groundplum Milkvetch - Astragalus crassicarpus var. crassicarpus

No photos are currently available
If you have a high quality photo of this species, are confident in the identification, and would like to submit it for inclusion on the Montana Field Guide, please send it to us using our online photo submission tool.

Native Species

Global Rank: G5T5
State Rank: S3S4
(see State Rank Reason below)

Agency Status


External Links

State Rank Reason (see State Rank above)
Astragalus crassicarpus variety crassicarpus occurs predominately in central and eastern Montana. Plants grow in relatively common habitats such as grasslands, sagebrush steppe, and stoney soil under Ponderosa Pine stands. Populations appear to be stable and threats have not been identified. Current data on locations, populations, and threats would improve the ability to track the status of variety crassicarpus.
  • Details on Status Ranking and Review
    Groundplum Milkvetch (Astragalus crassicarpus var. crassicarpus) Conservation Status Review
    Review Date = 09/18/2019
    View State Conservation Rank Criteria
    Range Extent

    ScoreF - 20,000-200,000 sq km (~8,000-80,000 sq mi)

    Comment173,312 square kilometers

    Area of Occupancy

    ScoreD - 6-25 4-km2 grid cells

    CommentPlant occurs in 21 of the 30,590 4x4 square-kilometer grid cells that cover Montana.

    Number of Populations

    ScoreC - 21 - 80

    Comment24 observations are identified to variety crassicarpus, while other observations are only identified to the species-level.

    Number of Occurrences or Percent Area with Good Viability / Ecological Integrity

    ScoreC - Few (4-12) occurrences with excellent or good viability or ecological integrity

    Comment5 observations assumed of good viability based on descriptor of 'common'.


    ScoreU - Unknown

General Description
PLANTS: A short, perennial forb that grows from a well branched caudex atop of a tap root. Plants are 5-40 cm and grow prostrate to ascending to erect with showy flowers and an inflated, round seed pod.

LEAVES: Pinnately dissected, with 13-21 leaflets which are oblanceolate to linear. Leaflets have (basifixed) hairs which make the plant appear slightly grayish. The leaf sheaths (stipules) are 3-8 mm long, lanceolate, and not fused around the stem. The leaves are usually taller and surpass the inflorescence.

INFLORESCENCE: A subcapitate to loose raceme arising from leaf axils with 5-20 flowers. Flowers are long, 22-30 mm, and either predominately purple or white with purple-tips. The banner petal is 22–30 mm long and moderately reflexed. The keel petal is 14–20 mm long. Sepals are 2-4 mm longs with black and/or white strigose hairs.

Montana plants are of variety crassicarpus or paysonii.

Sources: Lesica et al. 2012; Dorn 2001; and Flora of the Great Plains 1986.

Diagnostic Characteristics
In Montana Astragalus crassicarpus has two varieties (Lesica et al. 2012):

* var. crassicarpus has predominately purple flowers (petals). It is found on the Great Plains.

* var. paysonis has predominately white flowers (petals) with purple tips. It is mostly found in the western half of Montana.

Species Range

Range Comments
Alberta to Saskatchewan south to Arizona, New Mexico, Texas, and Arkansas (Lesica et al. 2012).

In Montana var. crassicarpus is found on the Great Plains (Lesica et al. 2012); although specimens displayed on the Consortium of Pacific Northwest Herbaria ( occur in central and eastern Montana.

Observations in Montana Natural Heritage Program Database
Number of Observations: 20

(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)

Grasslands and sagebrush steppe in the plains and valley zones of Montana (Lesica et al. 2012).

Food Habits
The ovary and legume are glabrous, and grow on short petioles. Legumes are 13-20 mm long, become inflated and nearly round (globose), possess a short narrow beak, and have 2 chambers. Legumes are fleshy inside, becoming leathery with age. Fruits generally lay on the ground at maturity.

Sources: Lesica et al. 2012; Dorn 2001; and Flora of the Great Plains 1986.

The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus vagans, Bombus appositus, Bombus auricomus, Bombus bifarius, Bombus borealis, Bombus centralis, Bombus fervidus, Bombus flavifrons, Bombus huntii, Bombus mixtus, Bombus nevadensis, Bombus rufocinctus, Bombus ternarius, Bombus terricola, Bombus occidentalis, Bombus pensylvanicus, Bombus griseocollis, and Bombus insularis (Macior 1974, Thorp et al. 1983, Mayer et al. 2000, Colla and Dumesh 2010, Wilson et al. 2010, Koch et al. 2012, Miller-Struttmann and Galen 2014, Williams et al. 2014).

  • 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.
    • Dorn, R. D. 2001. Vascular Plants of Wyoming. 3rd edition. Mountain West Publishing. Cheyenne, Wyoming. 412 pp.
    • 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.
    • Mayer, D.F., E.R. Miliczky, B.F. Finnigan, and C.A. Johnson. 2000. The bee fauna (Hymenoptera: Apoidea) of southeastern Washington. Journal of the Entomological Society of British Columbia 97: 25-31.
    • McGregor, R.L. (coordinator), T.M. Barkley, R.E. Brooks, and E.K. Schofield (eds). 1986. Flora of the Great Plains: Great Plains Flora Association. Lawrence, KS: Univ. Press Kansas. 1392 pp.
    • 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.
    • 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.
  • Web Search Engines for Articles on "Groundplum Milkvetch"
Login Logout
Citation for data on this website:
Groundplum Milkvetch — Astragalus crassicarpus var. crassicarpus.  Montana Field Guide.  .  Retrieved on , from