They are deciduous or evergreenshrubs, typically reaching 0.3-5 m tall. The leaves are small, 1-3 cm long, deeply three- to five-lobed, with revolute margins. The flowers are 1-2 cm diameter, with five white to pale yellow or pink petals and yellow stamens. The fruit is a cluster of dry, slender, leathery achenes 2-6 cm long.
The evergreen species were treated separately in the genus Cowania in the past; this genus is still accepted by some botanists.
Purshia stansburiana - Stansbury Cliffrose (syn. P. mexicana var. stansburiana, Cowania stansburiana). Idaho south to California, Arizona and New Mexico.
Purshia subintegra (possibly a hybrid between P. pinkavae and P. stansburiana). Arizona.
Purshia tridentata - Antelope Bitterbrush. British Columbia south to California and New Mexico.
The classification of Purshia within the Rosaceae is presently unclear. The genus was originally placed in the subfamily Rosoideae, and later in subfamily Dryadeae along with the genera Cercocarpus, Chamaebatia and Dryas, all genera sharing root nodules that host the nitrogen-fixingbacteriumFrankia. However, recent genetic research indicates that Dryadeae may be polyphyletic, with Dryas not closely related to the other genera.
<gallery>
Image:Purshia_tridentata_8234.jpg|P. tridentata, Lava Beds National Monument
Image:Purshia stansburiana 1.jpg|P. stansburiana, Red Rock Canyon, Nevada
Image:Purshia stansburiana 3.jpg|P. stansburiana, Red Rock Canyon, Nevada
Image:Purshia stansburiana 4.jpg|P. stansburiana, Red Rock Canyon, Nevada
</gallery>
Encyclopedia
top
