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.
Geohintonia mexicana is a species of cacti, the only species in the genus Geohintonia. This genus is named after its discoverer George S. Hinton. As its specific epithet suggests, the plant is found in Mexico, where it grows on gypsum hills near Galeana.
Obregonia, the artichoke cactus, is a monotypic genus of cacti, containing the species Obregonia denegrii. The species is endemic to the state of Tamaulipas in Mexico.
Strombocactus disciformis is a rare species of cacti and the only species of the genus Strombocactus. The plant originates from Central and Northeast Mexico.
Selenicereus megalanthus, synonym Hylocereus megalanthus, is a cactus species in the genus Selenicereus that is native to northern South America, where it is known, along with its fruit, by the name of pitahaya. The species is grown commercially for its yellow fruit, but is also an impressive ornamental climbing vine with perhaps the largest flowers of all cacti.
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.
Selenicereus grandiflorus is a cactus species originating from the Antilles, Mexico and Central America. The species is commonly referred to as queen of the night, night-blooming cereus, large-flowered cactus, sweet-scented cactus or vanilla cactus. The true species is extremely rare in cultivation. Most of the plants under this name belong to other species or hybrids. It is often confused with the genus Epiphyllum.
Aztekium ritteri is a species of cactus native to the Mexican state of Nuevo León.
Pelecyphora sneedii is a rare species of cactus known by the common names Sneed's pincushion cactus and carpet foxtail cactus. It is endemic to the Chihuahuan Desert of the southwestern United States and northwestern Mexico. It is a small, variable cactus with a lengthy taxonomic history, and is often subdivided into a number of subspecies or varieties. It is usually found on steep, rocky habitats, primarily of limestone geology, in desert scrub or coniferous forest. A species of conservation concern, P. sneedii faces threats from poaching, urban encroachment, and wildfires.
Rhipsalidopsis gaertneri, synonyms Schlumbergera gaertneri and Hatiora gaertneri, is a species of epiphytic cactus which belongs to the tribe Rhipsalideae within the subfamily Cactoideae of the Cactaceae. Together with the hybrid with R. rosea, Rhipsalidopsis × graeseri, it is known, in English speaking countries in the Northern Hemisphere, as Easter cactus or Whitsun cactus and is a widely cultivated ornamental plant. It has received the Royal Horticultural Society's Award of Garden Merit.
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.
Opuntia macrocentra, the long-spined purplish prickly pear or purple pricklypear, is a cactus found in the lower Southwestern United States and Northwestern Mexico. A member of the prickly pear genus, this species of Opuntia is most notable as one of a few cacti that produce a purple pigmentation in the stem. Other common names for this plant include black-spined pricklypear, long-spine prickly pear, purple pricklypear, and redeye prickly pear.
Leucostele terscheckii, commonly known as the cardon grande cactus or Argentine saguaro, is a large cactus native to South America and popular in cultivation.
Sclerocactus mesae-verdae, the Mesa Verde cactus or Mesa Verde fishhook cactus, is a species of cactus native to northwestern New Mexico and southwestern Colorado. It is known only from Montezuma County (Colorado) and San Juan County. Much of the New Mexico part of the range lies inside land controlled by the Navajo Nation. The Colorado populations lie close to Mesa Verde National Park.
Ferocactus macrodiscus is a species of cactus in the genus Ferocactus from Guanahuato and Oaxaca States, Mexico.
Oreocereus trollii, commonly known as the Old Man of the Andes cactus, is a species of cacti native to Argentina and Bolivia. Though listed as Least Concern by the IUCN, the plant is collected extensively, and in some areas is threatened.
Lobivia ferox, is a species of Lobivia found in Bolivia and Argentina.
Opuntia sulpurea falls under the Opuntia, or prickly pear, genus within the family Cacataceae named such because of their round shape, green color, and long thick spines. Opuntia sulphurea is the widest spread of the Opuntia that can be found in and around Argentina, occupying mostly arid areas of the region from the plains in the Western portion of Argentina up to much higher altitudes on the Eastern side of the Andes mountain range. As a result of its ability to survive in such a diverse array of environments there are several subspecies of O. sulphurea that are identifiable based on the number of spine per areole, for example. A commonality across the three is a bright yellow flower, often considered to be the color of sulfur, from which the species name is derived. As with several other species of Opuntia, these prickly pears tend to grow in groups, forming clumps that can reach one to two meters in diameter, but while other species within the genus grow upwards as well O. sulphurea tend to stay low to the ground. As a result of its tendency to grow in dry, arid, and rocky areas this cactus has evolved to be very resilient, not even suffering from the effects of agriculture, i.e. cattle grazing, on lower altitude subpopulations.
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.
