Silky Locoweed - Oxytropis sericea

Silky Locoweed
Oxytropis sericea Nutt.

Family: Fabaceae, Pea
Genus: Oxytropis

Description
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; wings greatly widened, notched with
blunt point. Calyx 9-13 mm long, the teeth linear-lance-
shaped to oblong, 1.5-5 mm long.
Flowering time: June-July.

Fruits: pod, 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.

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

Toxic plant: see below.

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Contents
Identification
English Names Index
Scientific Names Index
Family Index

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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.