Bent-flowered Milkvetch - Astragalus vexilliflexus
(see State Rank Reason below)
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.
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 et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX
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.
BC to SK south to ID, WY and SD (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Observations in Montana Natural Heritage Program Database
Number of Observations:
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(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).
- 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.
- 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.
- 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.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?
- Ament, R.J. 1995. Pioneer Plant Communities Five Years After the 1988 Yellowstone Fires. M.Sc. Thesis. Bozeman, MT: Montana State University. 216 p.
- Culver, D.R. 1994. Floristic analysis of the Centennial Region, Montana. M.Sc. Thesis. Montana State University, Bozeman. 199 pp.
- Jones, W. W. 1901. Preliminary flora of Gallatin County. M.S. Thesis. Bozeman, MT: Montana State College. 78 pp.
- 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.