''Echinocactus horizonthalonius'' is a species of

cactus A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Gree ...

known by several common names, including devilshead, turk's head cactus, blue barrel cactus, eagle's claw,Baker, M. (2007)
A multivariate study of morphological characters for ''Echinocactus horizonthalonius'' and ''E. texensis'' (Cactaceae).
USFWS. horse maimer, horse crippler, and ''visnaga meloncillo''. It is native to the southwestern United States and northern Mexico, where it occurs in

Chihuahuan Desert The Chihuahuan Desert ( es, Desierto de Chihuahua, ) is a desert ecoregion designation covering parts of northern Mexico and the southwestern United States. It occupies much of far West Texas, the middle to lower Rio Grande Valley and the lo ...

and

Sonoran Desert The Sonoran Desert ( es, Desierto de Sonora) is a desert in North America and ecoregion that covers the northwestern Mexican states of Sonora, Baja California, and Baja California Sur, as well as part of the southwestern United States (in Ariz ...

habitats, particularly on

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

substrates. One of its

varieties Variety may refer to: Arts and entertainment Entertainment formats * Variety (radio) * Variety show, in theater and television Films * ''Variety'' (1925 film), a German silent film directed by Ewald Andre Dupont * ''Variety'' (1935 film), ...

is a federally listed endangered species of the United States.

Description

This cactus is gray-green to blue-gray in color and spherical, hemispherical, columnar, or flat-topped in shape. It reaches a maximum size of about 45 centimeters tall by 20 wide. The body is made up of curving sections that twist around the body in a

helical Helical may refer to: * Helix, the mathematical concept for the shape * Helical engine, a proposed spacecraft propulsion drive * Helical spring, a coilspring * Helical plc, a British property company, once a maker of steel bar stock * Helicoil A t ...

fashion. These sections are lined with

areole 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 - W ...

s bearing up to 10 spines each. The pink, gray, or brown spines may be over 4 centimeters long. The bright pink to

magenta Magenta () is a color that is variously defined as pinkish- purplish- red, reddish-purplish-pink or mauvish-crimson. On color wheels of the RGB (additive) and CMY (subtractive) color models, it is located exactly midway between red and blu ...

flowers are up to 7 to 9 centimeters wide.''Echinocactus horizonthalonius''
Flora of North America. Flowers open around midday and close for the night. They also open after the plant receives rainfall, and although most of the flowers occur in June, they may bloom again in late summer and fall if rain occurs.USFWS
''E. h.'' var. ''nicholii'' Five-year Review.
July 2009. The fruit is hairy or woolly and pink or red in color. ;Varieties The species is generally divided into two varieties. *The more common, ''Echinocactus horizonthalonius'' var. ''horizonthalonius'', can be found in

habitats, from

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

, through

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ke ...

, into

Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...

and Northeastern Mexico
USDA: ''Echinocactus horizonthalonius'' var. ''horizonthalonius'
*The rare ''Echinocactus horizonthalonius'' var. ''nicholii'', Nichol's turk's head cactus, is known only from three

populations in southeastern Arizona, and one in Sonora, Mexico. It is federally listed as an endangered species of the United States. Some populations are protected within Ironwood Forest National Monument in Pinal and Pima Counties in Arizona. Threats to the species include limestone mining, offroading, and collection of specimens for their showy flowers. Buffelgrass is also a major threat to the species, due to its introduction of fire to the landscape. There has been some success in conserving this variety, mainly by suppressing buffelgrass.

References

External links

USDA Plants profile — ''Echinocactus horizonthalonius'' (devilshead)The Nature Conservancy: ''Echinocactus horizonthalonius''.

Center for Plant Conservation: ''Echinocactus horizonthalonius''.

''Echinocactus horizonthalonius'' — U.C. Photo gallery
horizonthalonius Cacti of the United States Cacti of Mexico Flora of the Chihuahuan Desert Flora of the Sonoran Deserts North American desert flora Flora of Arizona Flora of New Mexico Flora of Sonora Flora of Texas {{Cactus-stub