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Montana Field Guides

Groundplum Milkvetch - Astragalus crassicarpus var. paysonii

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Native Species

Global Rank: G5TNR
State Rank: S4

Agency Status


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

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

Species Range

Range Comments
BC and AB south through MT (where common), WY, SD, CO, NM, and barely into the western parts of SD, NE and OK (Kartesz 2009).

In Montana var. paysonis is mostly found in the western half of the state (Lesica et al. 2012); although, specimens displayed on the Consortium of Pacific Northwest Herbaria portal ( occur in western, northeastern, and southeastern Montana.

Observations in Montana Natural Heritage Program Database
Number of Observations: 18

(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)

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).

Reproductive Characteristics
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.

  • 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.
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Citation for data on this website:
Groundplum Milkvetch — Astragalus crassicarpus var. paysonii.  Montana Field Guide.  .  Retrieved on , from