Lupines have numerous flowers in usually tall clusters, the color mostly white, yellowish, or pink to blue or violet. The banner of the flower is has the sides generally turned back, from sharply to only slightly bent back from the 2 wings. The wings are usually more or less completely enclosing the keel. The fruits are pods, somewhat flattened, hairy, one- to usually several-seeded, commonly constricted between the seeds. The genus are annual herbs or herbaceous to semi-shrubby perennials with palmately compound leaves of about 5-17 leaflets. The genus has most species in N. America, but is represented on all continents except Australia. Of the about 100 species of Lupinus worldwide, only a few are appropriate as forage. Some are bitter and potentially deadly to livestock due to their high alkaloid content. Lupinus is a genus of economic importance, some forms being attractive cultivated perennials. Among our native species, L. polyphyllus is fairly easily grown in moist areas and desirable as a garden subject. The seeds are readily eaten by many kinds of animals, although certain species are reputedly poisonous, especially the pods. One of our species has been introduced as a sandbinder along the coast, and several are highly regarded as leguminous cover crops.
Guide to Identify Presented Species of Genus Lupinus
TALL PLANTS, FLOWERS WITH A CONSPICUOUS HUMP AT BASE
L. arbustus Long-spurred Lupine Stems 20-50 cm tall, finely short-flat-hairy to grayish-flat-silky-hairy.
Flowers 8-11 mm long, white or bluish-tinged. Banner short-hairy on the back.
Leaves with 7-11 leaflets, short-hairy on the lower surface and hairless above.
TALL PLANTS, FLOWERS WITHOUT HUMP AT BASE
L. argenteus Silvery Lupine Stems 50-100 cm tall, flat-hairy to almost silky, often grayish-hairy.
Flowers 9-11 mm long. Calyx flat-silky-hairy. Banner mostly hairless.
Leaves with 6-9 leaflets, hairless above to short-flat-hairy on both surfaces.
L. sericeus Silky Lupine Stems 20-70 cm tall, silvery from spreading to flat hairs of two distinct lengths.
Flowers 10-12 mm long, on stalks 4-7 mm long. Banner silky-hairy on the back.
Leaves with 7-9 leaflets, about equally flat silky-hairy on the two surfaces.