Riverside lupine (also known as streambank lupine), Lupinus rivularis, is common throughout Northern California, Oregon and Washington, west of the mountains. It is considered endangered in British Columbia. Commonly found near streams, marshes and other wet areas, riverside lupine prefers sunny sites with gravely or sandy well-drained soil. It blooms from March through July with erect spikes of pea-like flowers in shades of violet to blue. It is a welcome self-seeder in the Buck Lake Native Plant Garden and is found in several locations, most notably the bed anchored by the huge Douglas fir and in the nearby camas meadow.

Lupinus rivularis is a pollen and necter source for bumblebees and other native pollinators. Its seeds are a eaten by a number of birds. It is also a butterfly host plant for the orange sulphur and the western tailed blue.