Lupinus caudatus, commonly known as tailcup lupine, is a perennial herb native to a variety of habitats in western North America, including open hillsides, road cuts, and moderately moist meadows, often associated with ponderosa pine, as well as sagebrush steppe and montane habitats. It is characterized by its distinctive purple-blue flowers with a short spur, which bloom from May to June, and its palmately compound leaves. The plant typically grows to a height of 1-2 feet (30-60 cm) and is known for its ability to fix nitrogen in the soil, improving soil fertility.

Tailcup lupine is valued for its ornamental flowers and its role in habitat restoration and soil improvement. It is often used in wildflower mixes for naturalized areas and is beneficial for pollinators. In cultivation, it prefers full sun to partial shade and requires well-drained soils. While it is drought-tolerant once established, it benefits from moderate moisture. Gardeners should be aware of its toxicity to livestock, as it contains the alkaloid anagyrine, which can cause "crooked calf" disease. It is generally low-maintenance but can be susceptible to fungal diseases in overly moist conditions.CC BY-SA 4.0