Streamside lupine is a robust, stout, annual legume that provides low to moderate height forage and ground cover. It has white tips on its blue flowers in contrast to the all-blue flowers of large-leaf lupine Lupinus polyphyllus. Seed size is large approximately 30,000 seeds per pound. Streamside lupine grows where annual rainfall ranges between 18-40 inches or higher and is most dominate on well drained, gravelly or loaming soil sites with good internal drainage. It is classified as a facultative wetland species (Guard, 1995). Mature plants range from 80-90 cm in height but can grow taller under optimal growing conditions. Habitat consists of streambanks, creeks, river-bars, and sloping roadsides in lower elevations of the Pacific coast from southeastern Alaska to southern California.
Streamside lupine unlike many lupine species is compatible with annual and perennial native grasses, forbes, legumes and tree plantings. Therefore, it is highly recommended as a component in native blends and mixtures where legumes are required. Streamside lupine provides excellent habitat for pollinating and feeding insects and birds.