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.
Echinopsis is a genus of cacti native to South America, sometimes known as hedgehog cactus, sea-urchin cactus or Easter lily cactus. As of October 2023, there are about 20 accepted species, ranging from large and treelike types to small globose cacti. The name derives from echinos hedgehog or sea urchin, and opsis appearance, a reference to these plants' dense coverings of spines.
Pereskia is a small genus of about four species of cacti that do not look much like other types of cacti, having substantial leaves and non-succulent stems. The genus is named after Nicolas-Claude Fabri de Peiresc, a 16th-century French botanist. The genus was more widely circumscribed until molecular phylogenetic studies showed that it was paraphyletic. The majority of species have since been transferred to Leuenbergeria and Rhodocactus. Although Pereskia does not resemble other cacti in its overall morphology, close examination shows spines developing from areoles, and the distinctive floral cup of the cactus family.
Didiereaceae is a family of flowering plants found in continental Africa and Madagascar. It contains 20 species classified in three subfamilies and six genera. Species of the family are succulent plants, growing in sub-arid to arid habitats. Several are known as ornamental plants in specialist succulent collections. The subfamily Didiereoideae is endemic to the southwest of Madagascar, where the species are characteristic elements of the spiny thickets.
Epiphyllum is a genus of epiphytic plants in the cactus family (Cactaceae), native to Central America and South America. Common names for these species include climbing cacti, orchid cacti and leaf cacti, though the latter also refers to the genus Pereskia.
In 1984, the International Organization for Succulent Plant Study set up a working party, now called the International Cactaceae Systematics Group, to produce a consensus classification of the cactus family, down to the level of genus. Their classification has been used as the basis for systems published since the mid-1990s. Treatments in the 21st century have generally divided the family into around 125–130 genera and 1,400–1,500 species, which are then arranged in a number of tribes and subfamilies. However, subsequent molecular phylogenetic studies have shown that a very high proportion of the higher taxa are not monophyletic, i.e. they do not contain all of the descendants of a common ancestor. As of August 2023, 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.
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.
Selenicereus, sometimes known as moonlight cactus, is a genus of epiphytic, lithophytic, and terrestrial cacti, found in Mexico, Central America, the Caribbean and northern South America. The term night-blooming cereus is also sometimes used, but this is also used for many night-blooming cacti, including Epiphyllum and Peniocereus. In 2017, the genus Hylocereus was brought into synonymy with Selenicereus. A number of species of Selenicereus produce fruit that is eaten. The fruit, known as pitaya or pitahaya in Spanish or as dragon fruit, may be collected from the wild or the plants may be cultivated.
Weberocereus is genus of cacti. It produces a green and white flower and is found mainly in Costa Rica and Nicaragua.
Pereskiopsis is a genus of cactus in the subfamily Opuntioideae. Unlike typical cacti, it has persistent fleshy leaves. The genus name refers to its resemblance to the genus Pereskia. Most species are found in Mexico south through Guatemala to Honduras, with one species in Bolivia. The incorrect spelling Peireskiopsis has also been used.
Brasiliopuntia is a genus in the cactus family, Cactaceae. It contains only one species, Brasiliopuntia brasiliensis.
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.
Rhodocactus grandifolius is a species of cactus native to eastern and southern Brazil. Like all species in the genus Rhodocactus and unlike most cacti, it has persistent leaves. It was first described in 1819. It is grown as an ornamental plant and has naturalized outside its native range.
Rhodocactus bahiensis is a species of tree-like cactus that is endemic to the Brazilian state of Bahia. First described as Pereskia bahiensis, it was transferred to Rhodocactus in 2016. Like all species in the genus Rhodocactus, and unlike most cacti, it has persistent leaves. In its native locality, it is used to form hedges.
Rhodocactus stenanthus is a species of cactus that is endemic to Brazil. First described as Pereskia stenantha, it was transferred to Rhodocactus in 2016. Like all species in the genus Rhodocactus, and unlike most cacti, it has persistent leaves. In its native locality, it is sometimes used in hedges.
Lophocereus marginatus is a species of plant in the family Cactaceae. It is sometimes called Mexican fencepost cactus.
Leuenbergeria bleo, formerly Pereskia bleo, is a leafy cactus, native to the shady, moist forests of Central America, that grows to a woody, prickly shrub about 2 m tall with large, orange flowers resembling rose blossoms.
Leuenbergeria is a genus of flowering plant in the family Cactaceae, mostly native around the Caribbean. Unlike most cacti, it has persistent leaves and develops bark on its stems early in its growth. The genus was created in 2012 by Joël Lodé. Before the creation of Leuenbergeria as a genus, the species within it were included in a broadly circumscribed genus, Pereskia. Leuenbergeria is the only genus in the subfamily Leuenbergerioideae.
Rhodocactus nemorosus is a species of flowering plant in the cactus family Cactaceae, native to southern Brazil, Paraguay, Uruguay and northeast Argentina. Like all species in the genus Rhodocactus and unlike most cacti, it has persistent leaves. It was first described by Nicolás Rojas Acosta in 1897 as Pereskia nemorosa, and transferred to Rhodocactus in 2016.
Rhodocactus sacharosa, synonym Pereskia sacharosa, is a species of flowering plant in the cactus family Cactaceae, native from Bolivia and west-central Brazil to Paraguay and northern Argentina. Like all species in the genus Rhodocactus and unlike most cacti, it has persistent leaves. It was first described in 1879.
