Silky Locoweed
Oxytropis sericea Nutt.
Family: Fabaceae, Pea
Genus: Oxytropis
Other names: silvery oxytrope, white pointloco
Nomenclature: sericea = silky
Nativity / Invasiveness: Montana native plant
Poisonous plant
No medicinal data

General: plant height: 10-30 cm tall. Growth habit: erect perennial from branched root crown, often growing in tufts. Stems: leafless, grayish with dense, flat, silky hairs.

Leaves: basal, 5-30 cm long, pinnately divided into 11-17 narrowly elliptic leaflets, 10-35 mm long, grayish with dense, flat, silky hairs. Stipules membranous, 10-30 mm long, joined to the leaf stalk for 3/4 of their length.

Flowers: white to yellowish, often pinkish-tinged, 15-27 mm long, in spikelike clusters, compactly 6 to 27-flowered, usually considerably elongated in fruit. Keel often purplish-tipped. Banner erect, the wings greatly widened, notched with blunt point. Calyx 9-13 mm long, the teeth linear-lance-shaped to oblong, 1.5-5 mm long. June-July.

Fruits: pods, short-hairy, 15-25 mm long, short-beaked, 5-7 mm in diameter, fleshy when green, the wall hardened and nearly 1 mm thick when dried.


Prairie land to drier subalpine meadows and slopes, in most parts of MT. Also from NM to n. Canada.
Poisonous Properties

Locoweed has caused a number of problems in cattle, horses, and sheep. Swainsonine, an indolizidine alkaloid, inhibits alpha-mannosidase in animal bodies, which can lead to disruption of cellular function. Locoism is a chronic disease that causes depression, incoordination, and nervousness under stress. Death can result. The cellular problems occur most readily in tissues of the nervous system. Pregnant animals often abort or give birth to young with congenital deformities. Congestive right heart disease occurs at high altitudes. The blooms and mature fruit of locoweed have higher quantities of the toxin swainsonine than do the leaves. The concentration of this toxin remains constant in leaves throughout the grazing season.

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