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.
Acharagma is a genus of two cactus species from northern Mexico.
Cleistocactus is a genus of flowering plants in the cactus family Cactaceae, native to mountainous areas - to 3,000 m (9,843 ft) - of South America. The name comes from the Greek kleistos meaning closed because the flowers hardly open.
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.
Neoraimondia is a genus of medium to large cacti from Peru. The genus is named after the Italian-born Peruvian explorer, naturalist, and scientist, Antonio Raimondi.
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.
Parodia is a genus of flowering plants in the family Cactaceae, native to the eastern slopes of the Andes in northwestern Argentina and southwestern Bolivia and in the lowland pampas regions of northeastern Argentina, southern Brazil, eastern Paraguay, and Uruguay. This genus has about 65 species, many of which have been transferred from Eriocactus, Notocactus and Wigginsia. They range from small globose plants to 1 m (3 ft) tall columnar cacti. All are deeply ribbed and spiny, with single flowers at or near the crown. Some species produce offsets at the base. They are popular in cultivation, but must be grown indoors where temperatures fall below 10 °C (50 °F).
Espostoopsis is a monotypic genus of cactus containing the single species Espostoopsis dybowskii. The generic name is formed from Greek opsis meaning "view", referring to its resemblance to the genus Espostoa, with which it is often confused. The plant is only known from northern Bahia, Brazil.
Mila caespitosa is a species of cacti and the only species of the genus Mila. Its generic name is an anagram of Lima, Peru, the city near which the plant is found. The genus was first thought to comprise 13 species, until recent studies suggest they form one very variable species.
Brasiliopuntia is a genus in the cactus family, Cactaceae. It contains only one species, Brasiliopuntia brasiliensis.
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 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.
Trichocereus macrogonus, synonym Echinopsis macrogonus, is a species of cactus found in Ecuador, Peru and Bolivia. Two varieties are accepted as of September 2023: var. macrogonus and var. pachanoi. Plants contain varying amounts of the psychoactive alkaloid mescaline. They have been used both ritually and in traditional medicine from pre-Columbian times. Trichocereus macrogonus is one of a number of similar species that may be called San Pedro cactus. Indigenous names include achuma and huachuma, although these too may be applied to similar species.
Gymnocalycium saglionis, the giant chin cactus, is a globular cactus species endemic to northwest Argentina.
Mammillaria elongata, the gold lace cactus or ladyfinger cactus, is a species of flowering plant in the family Cactaceae, native to central Mexico. Growing to 15 cm (6 in) tall by 30 cm (12 in) wide, it consists of densely packed clusters of elongated oval stems, covered in harmless yellow or brown spines, and in spring producing white or yellow flowers. It is among the most common and most variable of its genus in nature, and is a popular subject for cultivation. It has gained the Royal Horticultural Society's Award of Garden Merit.
Pelecyphora sneedii is a rare species of cactus known by the common names Sneed's pincushion cactus and carpet foxtail cactus.
Cereus ( "serious") is a genus of cacti including around 33 species of large columnar cacti from South America. The name is derived from Greek (κηρός) and Latin words meaning "wax", "torch" or "candle". Cereus was one of the first cactus genera to be described; the circumscription varies depending on the authority. The term "cereus" is also sometimes used for a ceroid cactus, any cactus with a very elongated body, including columnar growth cacti and epiphytic cacti.
Gymnocalycium baldianum, the spider-cactus or dwarf chin cactus, is a species of flowering plant in the cactus family Cactaceae, native to the Catamarca Province in Argentina.
Copiapoa hypogaea, the underground copiapoa, is a species of flowering plant in the genus Copiapoa in the cactus family (Cactaceae), native to northern Chile. It has gained the Royal Horticultural Society's Award of Garden Merit.
Gymnocalycium capillense is a species of Gymnocalycium cactus from Argentina.
