General: Perennial, 40-140 cm tall; stems 1 to several, erect or ascending, robust, variously pubescent, silky-strigose, silky-villous, or velutinous, sometimes also hirsute; caudex often woody.

Leaves: Basal and cauline (mostly), alternate, palmately compound, leaflets 5-9, oblanceolate, 2.5-7.5 cm long, silky-pubescent; blades petiolate, the cauline petioles 1.5-12 cm long, progressively reduced upwards.

Flowers: Inflorescence a raceme, short, compact, 0.3-2 cm long; pedicels 0.8-2 mm long; calyx 5.5-7.5 mm long, sparsely to densely pilose; corolla blue, occasionally white, glabrous, banner 5.5-8 mm long, with a pale to whitish patch, keel slightly longer than the banner; flowers June-September.

Fruits: Legume, 2-3 cm long, densely pilose; seeds mostly 2-5.

Ecology: Meadows, grasslands, sagebrush communities, woodlands, aspen/mixed conifer forests; 2100-2600 m (7000-8500 ft); Coconino county; western Canada, western and southwestern U.S.

Notes: Lupinus caudatus (tailcup lupine) is a perennial, 20-80 cm tall; stems are usually erect, branched, appressed- pubescent; leaves are mostly cauline, palmately compound with 5-9 leaflets, these oblanceolate to elliptic, glabrous to silky pubescent above, strigose to silky pubescent below; inflorescence is a raceme, several- to many-flowered; calyx is 5 mm long, distinctly spurred at the base, the spur about 1 mm long; corolla is blue- violet, deep blue, or occasionally white, the banner 10- 12 mm long; legume is 2.5-3 cm long, densely silky pubescent, seeds 5-6. It occurs in canyons, ponderosa pine forests and sandy soils in Apache, Cochise, Coconino, Gila, and Navajo counties up to 2900 m (9500 ft). Silky lupine is a host plant for Melissa blue, silvery blue, and Boisduval-s blue butterflies. It is an excellent species for rehabilitation of disturbed areas because of its ability to fix nitrogen.

Editor: Springer et al. 2008