A 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 Greek word κάκτος (káktos), a name originally used by Theophrastus for a spiny plant whose identity is now not certain. Cacti occur in a wide range of shapes and sizes. They are native to the Americas, ranging from Patagonia in the south to parts of western Canada in the north, with the exception of Rhipsalis baccifera, which is also found in Africa and Sri Lanka. Cacti are adapted to live in very dry environments, including the Atacama Desert, one of the driest places on Earth. Because of this, cacti show many adaptations to conserve water. For example, almost all cacti are succulents, meaning they have thickened, fleshy parts adapted to store water. Unlike many other succulents, the stem is the only part of most cacti where this vital process takes place. Most species of cacti have lost true leaves, retaining only spines, which are highly modified leaves. As well as defending against herbivores, spines help prevent water loss by reducing air flow close to the cactus and providing some shade. In the absence of true leaves, cacti's enlarged stems carry out photosynthesis.
The Cactoideae are the largest subfamily of the cactus family, Cactaceae. Around 80% of cactus species belong to this subfamily. As of August 2018, the internal classification of the family Cactaceae remained uncertain and subject to change. A classification incorporating many of the insights from the molecular studies was produced by Nyffeler and Eggli in 2010. Various revisions have been published since, e.g. to the tribe Hylocereeae and the tribe Echinocereeae. Classifications remained uncertain as of March 2019.
Cacteae is a tribe of plants of the family Cactaceae found mainly in North America especially Mexico. As of August 2018, the internal classification of the family Cactaceae remained uncertain and subject to change. A classification incorporating many of the insights from the molecular studies was produced by Nyffeler and Eggli in 2010.
Micranthocereus albicephalus is a species of plant in the family Cactaceae. It is endemic to Brazil. Its natural habitats are subtropical or tropical dry shrubland and rocky areas. It is threatened by habitat loss.
Uebelmannia buiningii is a species of plant in the family Cactaceae. It is endemic to Brazil. Its natural habitat is dry savanna. It is threatened by habitat loss.
Ferocactus wislizeni, the fishhook barrel cactus, also called Arizona barrel cactus, candy barrel cactus, and Southwestern barrel cactus, is a species of flowering plant in the cactus family Cactaceae, native to northern Mexico and the southern United States. It is a ball-shaped cactus eventually growing to a cylindrical shape, with spiny ribs and red or yellow flowers in summer.
Ferocactus glaucescens, the glaucous barrel cactus, is a species of flowering plant in the family Cactaceae, native to the limestone hills of Hidalgo, endemic to México. It is a spherical or cylindrical cactus growing to 60 cm (24 in) in diameter, with long yellow spines and yellow flowers in summer.
Ferocactus viridescens is a species of flowering plant in the cactus family Cactaceae. This rare barrel cactus is known by several common names, including coast barrel cactus, keg cactus and San Diego barrel cactus. Most of its native range in the United States is in San Diego County, California, where it is threatened by development, agriculture, and other alterations in its habitat. It is also found in northern Baja California, Mexico.
Soehrensia schickendantzii is a cactus found in northwestern Argentina in provinces of Salta and Tucumán at elevations of 1600 to 3200 meters.
Ferocactus latispinus is a species of barrel cactus native to Mexico. Originally described as Cactus latispinus in 1824 by English naturalist Adrian Hardy Haworth, it gained its current name in 1922 with the erection of the genus Ferocactus by American botanists Britton and Rose. The species name is derived from the Latin latus "broad", and spinus "spine". Ferocactus recurvus is a former name for the species.
Echinocactus horizonthalonius is a species of cactus known by several common names, including devilshead, turk's head cactus, blue barrel cactus, eagle's claw, horse maimer, horse crippler, and visnaga meloncillo. It is native to the southwestern United States and northern Mexico, where it occurs in Chihuahuan Desert and Sonoran Desert habitats, particularly on limestone substrates. One of its varieties is a federally listed endangered species of the United States.
Ferocactus peninsulae is a barrel cactus in the genus Ferocactus of the family Cactaceae.
Ferocactus robustus is a barrel cactus in the genus Ferocactus of the family Cacteae.
Ferocactus emoryi, known commonly as Emory's barrel cactus, Coville's barrel cactus and traveler's friend, is a barrel cactus in the genus Ferocactus.
Ferocactus fordii is a species of flowering plant in the family Cactaceae, native to Baja California in Mexico. It is spherical, growing to 50 cm (20 in) in diameter, with whitish-grey radial spines and solitary flowers of a deep rose pink, 4 cm (2 in) in diameter.
Ferocactus hamatacanthus, commonly named Turk's Head, is a barrel cactus in the tribe Cacteae.
Flora of the Sonoran Desert includes six subdivisions based on vegetation types. Two are north of the boundary between the United States and Mexico, and four are south of the boundary. The flora of the Colorado Desert are influenced by the environment of the very dry and hot lower areas of the Colorado River valley, which may be barren, treeless, and generally have no large cacti. Flora of the Arizona Upland are comparatively lush, with trees and large columnar cacti that can withstand winter frosts. Those subdivisions of the Sonoran Desert which lie south of the international border are characterized by plants that cannot withstand frost.
Ferocactus histrix, also known as Acitrón barrel cactus is a species of Ferocactus native to central Mexico. It is a large barrel cactus that can be commonly found throughout all the Central Mexican matorral. It produces an edible fruit appreciated for its sour taste.
Soehrensia huascha, is a species of Soehrensia in the Cactaceae family, found in north western Argentina. First published in Cactaceae Syst. Init. 29: 5 in 2013.
Melocactus ernesti is one of the Turk's cap cacti, and is native to Bahia and Minas Gerais States, Brazil. The lower body is green and has about 13 ribs or ridges, each with a row of spines usually about 1 to 2 inches long, but the spines can occasionally be as much as ten inches in length, exceeded only by Ferocactus emoryi subspecies rectispinus. Above this is the red, columnar capitulum which is perennial, composed of hundreds of small, tightly packed flowers and grows a little longer each year.
