Psorothamnus is a genus of plants in the legume family. These are shrubs and small trees. Many are known by the general common name indigo bush. Some are referred to as daleas, as this genus was once included in genus Dalea. These are generally thorny, thickly branched, strongly scented bushes. Most species bear lupinlike raceme inflorescences of bright purple legume flowers and gland-rich pods. Psorothamnus species are native to the southwestern United States and northern Mexico.