Flora of North America species comparison

Lupinus arboreus is known from the central California coast southward to northern Baja California; it was introduced as a sand binder and has become naturalized in northern California, Oregon, Washington, and southern British Columbia.

Lupinus arboreus grades into L. rivularis in the North Coast of California. Plants with yellow petals and sweet-smelling flowers are widely cultivated as a sand binder. Hairier plants from the western San Francisco Bay area with yellow banners and blue wings have been called var. eximius; plants with glabrous leaflets and purple petals have been called L. propinquus. Lupinus arboreus hybridizes with L. littoralis and probably other species. Seeds of L. arboreus species are toxic.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Lupinus sericeus is widespread and common from the southern interior mountains in British Columbia and southwestern Alberta southward to eastern Washington and eastern Oregon to northern New Mexico and northwestern Arizona, northeastern Nevada through Idaho and Wyoming to the Black Hills in South Dakota.

Plants with creamy or white flowers in southeastern Washington are known as subsp. asotinensis. D. Isely (1998) recognized this taxon based on petal color and distribution, but since white and yellow flowers occur throughout the range of Lupinus sericeus, it is not formally recognized here.

Lupinus pureriae C. P. Smith may be a hybrid derived in part from L. sericeus, according to an annotation by D. B. Dunn on the holotype (CAS0008254).

(Discussion copyrighted by Flora of North America; reprinted with permission.)