A cactus is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1,750 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.
Echinocereus is a genus of ribbed, usually small to medium-sized, cylindrical shaped cacti, comprising about 70 species native to the southern United States and Mexico in very sunny, rocky places. Usually the flowers are large and the fruit edible.
Ariocarpus is a small genus of succulent, subtropical plants of the family Cactaceae.
Cochemiea macdougallii is a species of cactus in the genus Cochemiea.
Pelecyphora, pincushion cactus or foxtail cactus is a genus of cacti, comprising 20 species. They originate from Mexico and the United States.
Disocactus is a genus of epiphytic cacti in the tribe Hylocereeae found in Central America, the Caribbean and northern South America. It should not be confused with Discocactus, which is a different genus.
Morangaya is a monotypic genus of ribbed, usually small to medium-sized, cylindrical shaped cacti, that is native to north western Mexico. The only species is Morangaya pensilis. It is found in the mountains and rocky hills.
Discocactus is a genus of tropical cacti. Discocactus plants are endemic to southern Brazil, eastern Bolivia, and northern Paraguay. These species are in the risk of extinction in the wild.
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. The main threats to cactus species are poaching, farming, mining developments, and climate change.
Opuntioideae is a subfamily of the cactus family, Cactaceae. It contains 15 genera divided into five tribes. The subfamily encompasses roughly 220–250 species, and is geographically distributed throughout the New World from Canada, to Argentina. Members of this subfamily have diverse habits, including small geophytes, hemispherical cushions, shrubs, trees, and columnar cacti consisting of indeterminate branches or determinate terete or spherical segments.
Ariocarpus agavoides is a species of cactus. It is endemic to Mexico. It grows in dry shrubland in rocky calcareous substrates. Some taxonomists place it in a separate genus as Neogomezia agavoides. The locals use the slime from the roots of the plants as glue to repair pottery. The sweet-tasting warts are eaten and often added to salads
Ariocarpus bravoanus is a species of cactus which is endemic to San Luis Potosí in Mexico. It grows in dry shrubland habitat on limestone substrates. It is endangered due to overcollecting.
Ariocarpus kotschoubeyanus is a species of plant in the family Cactaceae.
Schlumbergera opuntioides is a species of plant in the family Cactaceae. It is endemic to the coastal mountains of south-eastern Brazil where its natural habitats are humid forests and rocky areas. It is threatened by habitat loss. It is in the same genus as the popular house plant known as Christmas Cactus or Thanksgiving Cactus.
Trichocereus macrogonus var. pachanoi is a fast-growing columnar cactus found in the Andes at 2,000–3,000 m (6,600–9,800 ft) in altitude. It is one of a number of kinds of cacti known as San Pedro cactus. It is native to Ecuador, Peru and Colombia, but also found in Argentina, Bolivia, Chile and Venezuela and cultivated in other parts of the world. Uses for it include traditional medicine and traditional veterinary medicine, and it is widely grown as an ornamental cactus. It has been used for healing and religious divination in the Andes Mountains region for over 3,000 years.
Aztekium ritteri is a species of cactus native to the Mexican state of Nuevo León.
Cylindropuntia echinocarpa is a species of cactus known by the common names silver cholla, golden cholla, and Wiggins' cholla. It was formerly named Opuntia echinocarpa.
Many cacti are known to be psychoactive, containing phenethylamine alkaloids such as mescaline. However, the two main ritualistic (folkloric) genera are Echinopsis, of which the most psychoactive species occur in the San Pedro cactus group, and Lophophora, with peyote being the most psychoactive species. Several other species pertaining to other genera are also psychoactive, though not always used with a ritualistic intent.
Opuntia tortispina is a species of flowering plant in the family Cactaceae, native to the central United States. It was first described in 1856.
Pelecyphora macromeris, the nipple beehive cactus, is a species of cactus in the United States and Mexico. In the Chihuhuan Desert, it is common and has a wide range.
