Purshia (bitterbrush or cliff-rose) is a small genus of 5–8 species of flowering plants in the family Rosaceae which are native to western North America.

Description

Purshia species form deciduous or evergreen shrubs, typically reaching 0.3–5 m tall. The leaves are 1–3 cm long, deeply three- to five-lobed, with revolute margins. The flowers are 1–2 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 2–6 cm long. The roots have nodules that host nitrogen-fixing Frankia bacterium.

Taxonomy

Taxonomic history

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.

Modern classification

The classification of Purshia within the family Rosaceae has been unclear. It is now placed in the subfamily Dryadoideae.

Species

Purshia comprises the following species:

Hybrids

The following hybrid has been described:

Species names with uncertain taxonomic status

The status of the following species and hybrids is unresolved:

Distribution and habitat

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.

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