Lupinus sellulus, commonly known as the Donner Lake lupine, is a species of lupine native to the western United States. This herbaceous perennial is recognized for its attractive floral display and its role within its native ecosystems. It is a member of the diverse Lupinus genus, which is characterized by its distinctive pea-like flowers and palmately compound leaves. The Donner Lake lupine typically grows as an erect to spreading perennial, reaching heights of approximately 30 to 60 centimeters. Its stems are generally slender and can be sparsely to moderately hairy. The leaves are arranged alternately along the stem and are palmately compound, meaning they are divided into several leaflets that radiate from a single point, resembling an open hand. Each leaflet is typically oblanceolate to narrowly elliptic, measuring about 3 to 7 centimeters in length, and is often covered with fine hairs, giving them a somewhat soft texture. The undersides of the leaves may be more densely pubescent. The inflorescence of Lupinus sellulus is a terminal raceme, which is a cluster of flowers arranged along an elongated stem. The flowers themselves are zygomorphic, meaning they have bilateral symmetry, and are typically a vibrant blue to violet color, often with a white or yellowish central marking on the banner petal. Flowering usually occurs from late spring through summer, depending on elevation and local climate conditions. Following successful pollination, the plant produces fruits in the form of small, flattened pods, characteristic of the legume family. These pods contain a few seeds. Lupinus sellulus is primarily found in the Sierra Nevada mountain range of California and Nevada, with its distribution closely associated with the Donner Lake region, from which it derives its common name. It thrives in open, sunny locations, often found in meadows, open woodlands, and along roadsides at mid to high elevations. Its habitat requirements include well-drained soils, which can range from sandy to loamy. While it is adapted to its native mountain environments, it can also be cultivated in similar conditions in gardens, preferring full sun and moderate watering once established. Ecologically, Lupinus sellulus plays a role in its native habitat by providing nectar and pollen for pollinators, contributing to the biodiversity of the Sierra Nevada flora. Like other lupines, it is a nitrogen-fixing plant, meaning it has a symbiotic relationship with soil bacteria that convert atmospheric nitrogen into a form usable by plants, thereby enriching the soil. This characteristic can be beneficial in ecological restoration efforts or in garden settings where soil improvement is desired. While some lupine species have medicinal or culinary uses, such applications are not widely documented or recommended for Lupinus sellulus, and caution should be exercised due to the potential toxicity of some lupine species. Its primary significance remains its ornamental value and its contribution to the native plant communities of its range.