General: perennial from a well-branched crown, 50-100 cm tall. Stems several, simple to freely branched, more or less densely flat-hairy to almost silky, often grayish.
Leaves: alternate, the upper stalks not quite as long, the lower as much as to twice as long as the blades. Leaflets 6-9, narrowly lanceolate to oblanceolate, mostly 2-3 cm long, from hairless on the upper surface and moderately short-flat-hairy on the lower, to almost equally flat-short- to silky-hairy on both surfaces.
Flowers: many in slender clusters 10-15 cm long. The flowers almost whorled, 9-11 mm long, nearly white with bluish shading to light or dark blue. Flower stalks 3-6 mm long. Calyx flat-silky-hairy, the upper lip 2-toothed, the lower entire. Banner usually whitish-centered and hairless, fairly well bent back. Wings hairless. Keel usually hairy on the upper edge, only slightly or not at all protruding.
Fruits: pods, 1.5-2.5 cm long, very hairy. Seeds 2-5, about 4 mm long, pinkish-gray to light brown.
Ponderosa pine forest and meadows, in most parts of MT. Also from Alberta to c. OR, n.e. CA , NM and SD, common in the Great Basin.
ssp. argenteus var. argenteus:
Silvery 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.
ssp. argenteus var. argenteus Pursh: Plant usually not grayish-hairy. Calyx without hump on the upper base.
ssp. argenteus var. laxiflorus (Dougl. ex Lindl.) Dorn: Plant usually at least somewhat grayish-hairy. Leaves flat-hairy on both sides. Calyx with a hump on the upper base.
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