''Pelecyphora alversonii'' commonly known as cushion foxtail cactus or cushion fox-tail cactus, is a species of flowering plant in the family

Cactaceae A cactus (: cacti, cactuses, or less commonly, cactus) is a member of the plant family Cactaceae (), a family of the order Caryophyllales comprising about 127 genera with some 1,750 known species. The word ''cactus'' derives, through Latin, ...

, native to the southwestern United States.

Description

''Pelecyphora alversonii'' usually grows sprouting and forms underground, cylindrical offshoots with a diameter of 6–9 cm. The more or less spherical shoots reach heights of up to 7-25 centimeters. The plants have 18-33 radial spines per

areoles In botany, areoles are small light- to dark-colored bumps on cacti out of which grow clusters of spines. Areoles are important diagnostic features of cacti, and identify them as a family distinct from other succulent plants. Gordon Rowley - Wh ...

. The eight to ten central spines have a white to dark red or black tip and are 1.2 to 1.6 centimeters long. The twelve to 18 white marginal spines are 1.2 to 2 centimeters long. The flowers are magenta to pink and reach a diameter of around 3.2 centimeters. The ellipsoid fruits are green. Chromosome count is 2n = 22. File:Escobaria alversonii - Lone Cactus.jpg, '' P. alversonii'' in

Joshua Tree National Park Joshua Tree National Park is a List of national parks of the United States, US National Park located in southeastern California, straddling north-central Riverside County, California, Riverside County and part of southern San Bernardino County, ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

Distribution

''Pelecyphora alversonii'' is widespread in the United States in southeastern

in the

Mojave Desert The Mojave Desert (; ; ) is a desert in the rain shadow of the southern Sierra Nevada mountains and Transverse Ranges in the Southwestern United States. Named for the Indigenous peoples of the Americas, indigenous Mohave people, it is located pr ...

and neighboring

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

at elevations around 75–600 meters.

Taxonomy

The first description as ''Cactus radiosus'' var. ''alversonii'' by

John Merle Coulter John Merle Coulter, Ph. D. (November 20, 1851 – December 23, 1928) was an American botanist and educator. In his career in education administration, Coulter is notable for serving as the president of Indiana University and Lake Forest College ...

was published in 1894. The specific epithet alversonii honors the mineral explorer Andrew H. Alverson (1845–1916).

Nigel Paul Taylor Nigel Paul Taylor (born 1956) is a British botanist. He mainly focuses on the study of cacti. Taylor has been director of the Singapore Botanic Gardens since September 2011. He was previously curator of the Kew Gardens in London London is ...

placed the variety as a species in the genus ''Escobaria'' in 1997. David Aquino & Daniel Sánchez moved the species to ''Pelecyphora'' based on

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

studies in 2022. Further nomenclature synonyms are ''Mammillaria alversonii'' (J.M.Coult.) Zeiss. (1895), ''Mammillaria radiosa'' var. ''alversonii'' (J.M.Coult.) K.Schum. (1898), ''Mammillaria arizonica'' var. ''alversonii'' (J.M.Coult.) Davidson & Moxley (1923), ''Coryphantha alversonii'' (J.M.Coult.) Orcutt (1926), ''Mammillaria vivipara'' var ''vivipara'' var. ''alversonii'' (J.M.Coult.) L.D.Benson (1969), ''Escobaria vivipara'' var. ''alversonii'' (J.M.Coult.) D.R.Hunt (1978) and ''Escobaria alversonii'' (J.M.Coult.) N.P.Taylor (1997).

Conservation status

It is

vulnerable species A vulnerable species is a species which has been Conservation status, categorized by the International Union for Conservation of Nature as being threatened species, threatened with extinction unless the circumstances that are threatened species, ...

on the

California Native Plant Society The California Native Plant Society (CNPS) is a California environmental non-profit organization (501(c)(3)) that seeks to increase understanding of California's native flora and to preserve it for future generations. The mission of CNPS is to c ...

Inventory of Rare and Endangered Plants.

References

External links

* {{Taxonbar, from1=Q119735228, from2=Q1367220, from3=Q19859006 alversonii Flora of the Southwestern United States Cacti of the United States Flora of Arizona