Description
''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 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 root nodule, 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: * ''Purshia ericifolia'' (Torr. ex A.Gray) Henr. – Heath cliffrose (Texas) * ''Purshia glandulosa'' Curran – Desert bitterbrush (Nevada, Utah, Arizona) * ''Purshia mexicana'' (D.Don) Henr. – Mexican cliffrose (Mexico, Arizona) * ''Purshia pinkavae'' Schaack – D.J.Pinkava, Pinkava's cliffrose (Arizona) * ''Purshia plicata'' (D.Don) Henrard (syn. ''Cowania plicata'') – Antelope bush (Nuevo León, Mexico). * ''Purshia stansburyana'' (Torr.) Henr. – Stansbury cliffrose (Idaho south to California, Arizona and New Mexico) * ''Purshia tridentata'' (Pursh) DC. – Antelope bitterbrush (British Columbia south to California and New Mexico)Hybrids
The following Hybrid (biology), hybrid has been described: * ''Purshia'' × ''subintegra'' (Kearney) Henr. (''P. pinkavae'' × ''P. stansburyana'') – (Arizona)Species names with uncertain taxonomic status
The status of the following species and hybrids is unresolved: * ''Purshia ciliata'' Dennst. * ''Purshia mollis'' Lehm. * ''Purshia plicata'' (D.Don) Henr. * ''Purshia subintegra'' (Kearney) HenricksonDistribution 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.Gallery
References
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