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.
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.
Cleistocactus strausii, the silver torch or wooly torch, is a perennial flowering plant in the family Cactaceae. It is native to mountainous regions of Department Tarija, Bolivia, at 1,500–3,000 m (4,921–9,843 ft).
Bergerocactus emoryi is a species of cactus, known commonly as the golden-spined cereus, golden snake cactus, velvet cactus or golden club cactus. It is a relatively small cactus, but it can form dense thickets or colonies, with the dense yellow spines giving off a velvety appearance when backlit by the sun. From April to May, yellow, green-tinged flowers emerge, which transform into reddish, globular fruit. This species is native to the California Floristic Province, and is found in northwestern Baja California and a small part of California, in San Diego County and on the southern Channel Islands. Where the Mediterranean climate of the California Floristic Province collides with the subtropical Sonoran Desert near El Rosario, hybrids with two other species of cacti are found. It is the sole member of the monotypic genus Bergerocactus, named after German botanist Alwin Berger.
Weberocereus is genus of cacti. It produces a green and white flower and is found mainly in Costa Rica and Nicaragua.
Vatricania is a monotypic genus of flowering plants belonging to the family Cactaceae. It contains just one species, Vatricania guentheri. It has the common name of red tail cactus.
Oroya is a genus of cacti, native to Peru. The genus is widespread in the Peruvian Andes.
Weingartia is a genus in the family Cactaceae, with species native to Bolivia and Argentina. Molecular phylogenetic evidence suggests that it may be distinct from Rebutia. It is treated as a synonym of that genus by Plants of the World Online as of September 2023, but recognized as an alternative generic name in the third edition of the CITES Cactaceae Checklist. It may also be treated as Rebutia subg. Weingartia.
Echinopsis lageniformis, synonyms including Echinopsis scopulicola and Trichocereus bridgesii, is a cactus native to Bolivia. It is known as the Bolivian torch cactus. Among the indigenous populations of Bolivia, it is sometimes called achuma or wachuma, although these names are also applied to related species such as Trichocereus macrogonus which are also used for their psychedelic effects.
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.
Aztekium ritteri is a species of cactus native to the Mexican state of Nuevo León.
Lophocereus marginatus is a species of plant in the family Cactaceae. It is sometimes called Mexican fencepost cactus.
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.
Echinocereus dasyacanthus is a member of the cactus family, Cactaceae. It is one of about 2000 total species belonging to this family. The cactus is commonly known as Texas rainbow cactus because of the subtle rings or bands of contrasting colors along the stem of the plant. Not all Texas rainbow cacti have the "rainbow" coloration on their stems. Another common name is spiny hedgehog cactus.
Echinocereus stramineus is a species of cactus, wih stramineus meaning made of straw. There are various common names such as strawberry cactus, porcupine hedgehog cactus, straw-color hedgehog, and pitaya. The straw-colored spines distinguishes this particular plant from other Echinocereus. The aged spines may turn white in color and are very fragile.
Denmoza is a monotypic genus of cacti. Its only species, Denmoza rhodacantha, is native to northwest Argentina.
Echinopsis strigosa, is a species of Soehrensia in the cactus family. It is native to north western Argentina. It was first published in Cactaceae Syst. Init. 28: 31 in 2012.
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.
Echinocereus websterianus, commonly known as the San Pedro Nolasco hedgehog cactus or Webster's hedgehog cactus, is a species of cactus. It is named after American philanthropist Gertrude Webster, who cofounded the Desert Botanical Garden in Phoenix, Arizona.
Neoraimondia arequipensis, synonym Neoraimondia macrostibas, is a tree-like cactus native to western Peru. It was first described in 1835 as Cereus arequipensis.
