Purshia ( bitterbrush or cliff-rose) is a small genus of 5–8 species of in the family Rosaceae which are native to western North America.
Description
Purshia species form
deciduous or
evergreen , typically reaching tall. The
leaves are long, deeply three- to five-lobed, with revolute margins. The
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
which are 2–6 cm long. The roots have
root nodule 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 – 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 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) Henrickson
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.
==Gallery==
External links
