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

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of 5–8 species of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s in the family

Rosaceae Rosaceae (), the rose family, is a family of flowering plants that includes 4,828 known species in 91 genera. The name is derived from the type genus '' Rosa''. The family includes herbs, shrubs, and trees. Most species are deciduous, but som ...

which are native to western

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

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 Leaf, leaves, usually in the autumn; to the shedding of petals, aft ...

evergreen In botany, an evergreen is a plant which has Leaf, foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many diffe ...

shrub A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...

s, typically reaching tall. The

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

are long, deeply three- to five-lobed, with revolute margins. The

flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

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 (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...

is a cluster of dry, slender, leathery

achene An achene (; ), also sometimes called akene and occasionally achenium or achenocarp, is a type of simple fruit, simple dry fruits, dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and Dehi ...

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

nodule Nodule may refer to: * Nodule (geology), a small rock or mineral cluster * Manganese nodule, a metallic concretion found on the seafloor *Nodule (medicine), a small aggregation of cells *Root nodule Root nodules are found on the roots of plants, ...

s that host

nitrogen-fixing Nitrogen fixation is a chemical process by which molecular dinitrogen () is converted into ammonia (). It occurs both biologically and abiological nitrogen fixation, abiologically in chemical industry, chemical industries. Biological nitrogen ...

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 The rose subfamily Rosoideae consists of more than 850 species, including many shrubs, perennial herbs, and fruit plants such as strawberries and brambles. Only a few are annual herbs. The circumscription of the Rosoideae is still not wholly ce ...

. 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 The subfamily Dryadoideae consists of four genera in the family Rosaceae,. all of which contain representative species with root nodules that host the nitrogen-fixing bacterium ''Frankia''. They are subshrubs, shrubs, or small trees with a base ...

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 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

, where the species grow in dry climates from southeast

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

, south throughout the

western United States The Western United States (also called the American West, the Western States, the Far West, the Western territories, and the West) is List of regions of the United States, census regions United States Census Bureau. As American settlement i ...

northern Mexico Northern Mexico ( ), 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 Sur, Chihuahua (state), ...

Gallery

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

Lava Beds National Monument Lava Beds National Monument is located in northeastern California, in Siskiyou County, California, Siskiyou and Modoc County, California, Modoc counties. The monument lies on the northeastern flank of Medicine Lake Volcano, which is the largest ...

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