Purshia (bitterbrush or cliff-rose) is a small genus of 5âÂÂ8 species of flowering plants in the family Rosaceae which are native to western North America.
Purshia species form deciduous or evergreen shrubs, typically reaching tall. The leaves are long, deeply three- to five-lobed, with revolute margins. The flowers are 1âÂÂ2 cm in diameter, with five white to pale yellow or pink petals and yellow stamens. The fruit is a cluster of dry, slender, leathery achenes which are 2âÂÂ6 cm long. The roots have nodules that host nitrogen-fixing Frankia bacterium.
The genus was originally placed in the subfamily Rosoideae. In the past, the evergreen species were treated separately in the genus Cowania; this genus is still accepted by some botanists.
The classification of Purshia within the family Rosaceae has been unclear. It is now placed in the subfamily Dryadoideae.
Purshia comprises the following species:
The following hybrid has been described:
The status of the following species and hybrids is unresolved:
The genus is native to western North America, where the species grow in dry climates from southeast British Columbia, Canada, south throughout the western United States to northern Mexico.