''Purshia'' (bitterbrush or cliff-rose) is a small

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

of 5–8 species of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. They include all forbs (flowering plants without a woody stem), grasses and grass-like plants, a vast majority of ...

s in the family

Rosaceae Rosaceae (), the rose family, is a medium-sized family of flowering plants that includes 4,828 known species in 91 genera. The name is derived from the type genus ''Rosa''. Among the most species-rich genera are '' Alchemilla'' (270), '' Sorbu ...

which are native to western North America.

Description

''Purshia'' species form

deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, a ...

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, which ...

shrubs, typically reaching tall. The leaves are long, deeply three- to five-lobed, with revolute margins. The

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanism ...

s are 1–2 cm in diameter, with five white to pale yellow or pink petals and yellow stamens. The

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in partic ...

is a cluster of dry, slender, leathery

achene An achene (; ), also sometimes called akene and occasionally achenium or achenocarp, is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and indehiscent (they do not op ...

s which are 2–6 cm long. The roots have nodules that host

nitrogen-fixing Nitrogen fixation is a chemical process by which molecular nitrogen (), with a strong triple covalent bond, in the air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. At ...

Frankia ''Frankia'' is a genus of nitrogen-fixing bacteria that live in symbiosis with actinorhizal plants, similar to the '' Rhizobium'' bacteria found in the root nodules of legumes in the family Fabaceae. ''Frankia'' also initiate the forming of ro ...

'' bacterium.

Taxonomy

Taxonomic history

The genus was originally placed in the subfamily Rosoideae. In the past, the

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

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 ''Purshia tridentata'', with the common name bitterbrush, is a shrub in the genus '' Purshia'' of the family Rosaceae. It is native to mountainous areas of western North America. Common names include antelope bitterbrush, antelope bush, buckb ...

'' (Pursh) DC. – Antelope bitterbrush (British Columbia south to California and New Mexico)

Hybrids

The following

hybrid Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two diff ...

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 British Columbia (commonly abbreviated as BC) is the westernmost Provinces and territories of Canada, province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tota ...

, south throughout the

western United States The Western United States (also called the American West, the Far West, and the West) is the region comprising the westernmost states of the United States. As American settlement in the U.S. expanded westward, the meaning of the term ''the Wes ...

northern Mexico Northern Mexico ( es, el Norte de México ), commonly referred as , is an informal term for the northern cultural and geographical area in Mexico. Depending on the source, it contains some or all of the states of Baja California, Baja California ...

Gallery

Purshia_tridentata_8234.jpg, ''P. tridentata'',

Lava Beds National Monument Lava Beds National Monument is located in northeastern California, in Siskiyou and Modoc counties. The monument lies on the northeastern flank of Medicine Lake Volcano and has the largest total area covered by a volcano in the Cascade Range. ...

Purshia stansburiana 1.jpg, ''P. stansburiana'', Red Rock Canyon, Nevada Purshia stansburiana 4.jpg, ''P. stansburiana'', Red Rock Canyon, Nevada

References

External links

*
Jepson Flora Project: ''Purshia''
— ''(click 'taxon' to see treatments of California native species)'' Rosaceae genera {{rosaceae-stub