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Montana Field Guides

Bent-flowered Milkvetch - Astragalus vexilliflexus

Native Species

Global Rank: G4
State Rank: S4
(see State Rank Reason below)

Agency Status
MNPS Threat Rank:

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State Rank Reason (see State Rank above)
Numerous collections from a wide range in the state. Probably undercollected from eastern Montana. It is a frequent component of short-grass steppe.
General Description
Perennial often forming loose mats from a branched caudex. Herbage glabrate to densely strigillose. Stems prostrate to ascending, 5–30 cm. Leaves with 7 to 11 linear-lanceolate to narrowly elliptic leaflets, glabrate above, 5–12 mm long with acute tips; stipules lanceolate, 2–4 mm long, basally connate. Inflorescence ca. as long as the leaves, with 5 to 10 spreading flowers. Flowers white to purple; calyx black- and/or white-strigose; sepals 1–2 mm long; banner 6–8 mm long, erect; keel 3–6 mm long, purple-tipped. Legume spreading, narrowly ovate, white-strigillose, 6–13 mm long, flattened but swollen around the seeds (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Diagnostic Characteristics
Compact and pulvinate forms are similar to Astragalus kentrophyta, which differs in having stiffly pungent leaflets that are continuous with, not jointed, to the leaf rachis. The narrowly endemic A. vexilliflexus var. nubilus of central Idaho differs in being (sub)alpine, consistently compact and low to the ground, and in having loosely silky-villous hairs. This form should be sought in SW Montana.

Species Range

Range Comments
BC to SK south to ID, WY and SD (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 32

(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)

  • Additional ReferencesLegend:   View Online Publication
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    • Jones, W. W. 1901. Preliminary flora of Gallatin County. M.S. Thesis. Bozeman, MT: Montana State College. 78 pp.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • South, P.R. 1957. Food habits and range use of the mule deer in the Scudder Creek area, Beaverhead County, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 34 p.
    • Stewart, S.T. 1975. Ecology of the West Rosebud and Stillwater bighorn sheep herds, Beartooth Mountains, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 130 p.
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Citation for data on this website:
Bent-flowered Milkvetch — Astragalus vexilliflexus.  Montana Field Guide.  .  Retrieved on , from