General: plant height: 20-70 cm tall. Growth habit: erect perennial with a branching crown. Stems: usually several, simple or sparingly branched above, more or less silvery to slightly rust-colored from spreading to flat hairs, which generally are of two distinct lengths.
Leaves: alternate, the stalks of the lower ones as much as 3 times as long as the blades, reduced upward, the stalks of the upper leaves almost equal to the blades. Leaflets 7-9, oblanceolate, 3-6 cm long, mostly 3-6 mm broad, about equally flat silky-hairy on the two surfaces.
Flowers: lavender or blue, rarely yellowish or whitish, 10-12 mm long, on stalks 4-7 mm long. Clusters 10-15 cm long. Banner well upturned from the keel, silky-hairy on the back for over 2/3 of the length, usually whitish- or yellow-centered. Wings usually hairless, or with few hairs near the base. Keel edged with hairs, the tip upturned. Calyx silky, deeply 2-lipped, the lower lip entire, the upper 2-toothed.
Fruits: silky pods, 2-3 cm long and nearly 1 cm broad. Seeds 3-5, light pinkish-brown.
Moderately dry, open slopes, plains to montane zone, in w., n., c. and s. parts of MT. Also from B.C. and Alberta to CA, AZ and NM.
Silky lupine contains toxic alkaloids. The teratogenic alkaloid anagyrine is highest in the seeds, pods, and young leaves. The quinolizidine alkaloids implicated in lupine poisoning are found mostly in the seeds and pods. Large quantities of the plant material must be ingested in a short time to cause death. The alkaloids remain after drying, so that hay containing sufficient quantities of lupine can be toxic. General symptoms of lupine poisoning include dizziness and incoordination. Lupine seeds can be made edible by soaking and boiling the seeds in several changes of water. The toxic alkaloids are removed through several stages of cooking, and the process must be continued until no bitterness is left. In lupine seeds a lethal dose of lupanine has been determined to be about 100 mg/kg. If not properly cooked, 10 g of seeds may liberate more than 100 mg of lupanine. Keeler (1989) discusses a possible link between ingesting goat's milk and the occurrence of birth deformities in a baby. The goats may have been eating a lupine species that contained the teratogenic chemical anagyrine, which was passed through the woman when she drank goat's milk during pregnancy.
Our specimen belong to ssp. sericeus var. sericeus Pursh.
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