Rhizomatous perennial. Herbage sparsely to densely strigose with dolabriform hairs. Stems erect, 15–60 cm. Leaves with 11 to 23, narrowly elliptic leaflets, 1–4 cm long with blunt to rounded tips; stipules lanceolate-attenuate, 5–10 mm long. Inflorescence longer than the leaves, crowded with 30 to 100 spreading to declined flowers. Flowers ochroleucus; calyx black- and/or white-strigose; sepals 2–4 mm long; banner12–15 mm long, becoming moderately reflexed; keel 8–12 mm long, sometimes purple-tipped. Legume erect, elliptic to cylindric, 9–15 mm long, crowded (
Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
In Montana we have varieties
canadensis,
brevidens (Gand.) Barneby, and
mortonii (Nutt.) S. Watson.
Canadian Milkvetch -
Astragalus canadensis*Stems do not zigzag, 15-60 cm tall.
*Leaves have 11-23 narrowly elliptic leaflets.
*Leaf stipules are lanceolate-attenuate, 5-10 mm long.
*Flowers 30-100 spreading to declining in crowded racemes.
Wind River Milkvetch –
Astragalus oreganus, SOC
*Stems zigzag. 10-20 cm tall.
*Leaves have 5-15 broadly elliptic to nearly round leaflets (obovate) with blunt to rounded tips, and 2-forked hairs (dolabriform).
*Leaf stipules form a papery sheath at the base of each petiole, completely surrounding the stem (connate), 5-10 mm long.
*Flowers are yellowish-white (ochroleucus), 15-40, crowded in racemes, and cylindrical.
*Flowering stems are barely longer than the leaves.
Low Milkvetch -
Astragalus lotiflorus*Leaves with 5–15 linear-elliptic leaflets with acute tips.
*Leaf stipules lanceolate, 2–5 mm long, and distinct.
*Flowers are arranged in almost sessile racemes with 2–8 spreading flowers.
*Flowering stems are shorter than the leaves.
POLLINATORS 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).
