Oxytropis riparia
Sched. Herb. Fl. Ross. 6: 98. 1908.
Plants coarse, cespitose, clumps to 1 m diam., caulescent, (20–)60–100 cm, herbage minutely strigose; stems with 1 or 2+ internodes. Leaves subsessile, 5–15 cm; stipules foliaceous, light tan or grayish proximally, green distally, well separated on stem, 5–10 mm, sparsely to densely appressed to spreading pilose abaxially, margins ciliate; leaflets 11–17, alternate to subopposite, blades broadly lanceolate to oblanceolate, 10–38 × 3–12 mm, apex acute or subacute, surfaces sparsely to densely appressed to spreading-pilose abaxially, margins ciliate. Peduncles 8–15 cm, surpassing leaves, axis 3–20 cm in fruit, sparsely strigose to moderately pilose; bract linear-lanceolate, sparsely to densely pilose. Racemes (18–)20–50-flowered, elongate, lax, subsecund. Calyces scarcely enlarging in fruit, campanulate, white-strigose; tube 2–2.5 mm, lobes 1.2–1.5 mm. Corollas purplish, 6–7 mm. Legumes pendulous, stipitate, stipe 1–2.5 mm, sulcate adaxially, narrowly oblong, 15–20 × 4–5 mm, unilocular, papery, white- and/or black-strigulose. 2n = 16, 32.
Phenology: Flowering early–mid summer.
Habitat: Saline riparian lowlands with rush, greasewood, and cottonwood.
Elevation: 1100–2300 m.
Distribution
Introduced; Idaho, Mont., N.Dak., Utah, Wyo., Asia (Turkmenistan).
Discussion
Oxytropis riparia evidently was first discovered on ranches near Waterloo and Twin Bridges, in the valleys of the Jefferson and Ruby rivers in Madison County, Montana. The species is currently spreading and is to be expected at widely distributed locations throughout much of the American West. Plants at the Seedskadee National Wildlife Refuge, Wyoming, are eaten by sage grouse; they seem to prefer the flower buds but eat all parts of the plant.
Selected References
None.