A cactus is a member of the plant family Cactaceae, a family of the order Caryophyllales comprising about 127 genera with some 1,750 known species. 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.
Peperomia is one of the two large genera of the family Piperaceae. It is estimated that there are at least over 1,000 species, occurring in all tropical and subtropical regions of the world. They are concentrated in South and Central America, but may also be found in southern North America, the Caribbean islands, Africa, Oceania, and southern and eastern parts of Asia. The exact number of species is difficult to determine, as some plants have been recorded several times with different names, and new species continue to be discovered. Peperomias have adapted to many different environments and their appearances vary greatly. Some are epiphytes or lithophytes, and many are xerophytes or possess underground tubers (geophytes). Most species are compact perennial shrubs or vines.
Ferocactus is a genus of large barrel-shaped cacti, mostly with large spines and small flowers. There are about 30 species included in the genus. They are found in the southwestern United States and northwestern Mexico.
Arrojadoa is a genus of cacti, comprising 6 species and several varieties. It is named after the Brazilian botanist Miguel Arrojado Lisboa (1872–1932) who was superintendent of the Brazilian Railways at the time that Britton and Rose described the genus in 1920. The genus occurs only in northern Brazil and is found at rocky places, under shrubs, which support their frail stalk. They are subtropical plants, with very little frost tolerance.
Ariocarpus is a small genus of succulent, subtropical plants of the family Cactaceae.
Turbinicarpus is a genus of very small to medium-sized cacti, which inhabit the north-eastern regions of Mexico, in particular the states of San Luis Potosí, Guanajuato, Nuevo León, Querétaro, Hidalgo, Coahuila, Tamaulipas and Zacatecas.
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.
Samaipaticereus is a monotypic genus of cactus containing the sole species Samaipaticereus corroanus. It is known only from East Andean Bolivia and Peru.
Cylindropuntia is a genus of cacti, containing species commonly known as chollas, native to northern Mexico and the Southwestern United States. They are known for their barbed spines that tenaciously attach to skin, fur, and clothing. Stands of cholla are called cholla gardens. Individuals within these colonies often exhibit the same DNA, as they were formerly tubercles of an original plant.
Grusonia is a genus of opuntioid cacti, originating from the North American Deserts in Southwest United States and northern Mexico, including Baja California. Authors differ on precise boundaries of the genus, which has been included in Cylindropuntia. Corynopuntia, also known as club chollas, is now a synonym, with the genus originally being described by Knuth in 1935. Molecular phylogenetic studies suggest that it should be included in Grusonia, a view accepted by Plants of the World Online as of June 2021.
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.
Stenocereus thurberi, the organ pipe cactus, is a species of cactus native to Mexico and the United States. The species is found in rocky desert. Two subspecies are recognized based on their distribution and height. The Organ Pipe Cactus National Monument is named for the species. Cacti are minimally adapted to particular thermal niches, and are tremendously vulnerable to seasonal precipitation.
Echinopsis oxygona, also known as Eyries cactus, Easter lily cactus or sea-urchin cactus, is a species of flowering plant in the cactus family Cactaceae, native to south Brazil, Uruguay, Paraguay and northeastern Argentina. Some species that have been described separately, including Echinopsis eyriesii and Echinopsis tubiflora, are now considered to be synonymous. The features of the species include a large flower, with sharply pointed lavender or white petals, and a sweet scent.
Drosera gigantea, the giant sundew, is an erect perennial tuberous species in the carnivorous plant genus Drosera that is endemic to Western Australia. It grows in sandy soils at the margins of swamps and near granite outcrops along the Western Australian coast from Albany north to just south of Geraldton. D. gigantea produces small shield-shaped leaves along many lateral branches that look like a small tree. Individual plants can grow up to 0.2–1 m (0.7–3.3 ft) tall. Because of its tall, tree-like form, it is considered one of the largest Drosera species. It is also easily cultivated and enjoys damp, humid conditions often provided in greenhouses. White flowers emerge from August to November. The red tubers of this species can grow to be 3.8 cm (1.5 in) in diameter and may be a metre below ground.
Sclerocactus polyancistrus, the Mohave fishhook cactus or redspined fishhook cactus, is a species of flowering cactus in the genus Sclerocactus. It is found in the Mojave Desert in the Southwestern United States.
The Rhipsalideae are a small tribe of cacti, comprising four or five genera. They grow on trees (epiphytes) or on rocks (lithophytes), where they either hang down or form creeping or upright shrubs. Their flowers open in the day and remain open at night; they may be either radially symmetrical (regular) or bilaterally symmetrical (zygomorphic). The fruits are berry-like, fleshy with smallish seeds.
Cereus hildmannianus is a species of cactus from southern South America. Its distribution is uncertain but probably includes Brazil, Paraguay, Uruguay and Argentina.
Hatiora salicornioides, the bottle cactus, dancing-bones, drunkard's-dream, or spice cactus, is a species of flowering plant in the cactus family. A member of the tribe Rhipsalideae, it often grows as an epiphyte, natively in eastern Brazil and ornamentally elsewhere.
Cereus forbesii is a species of columnar cactus whose native range is Bolivia to N. Central Argentina.
Weingartia cintia is a small alpine cactus native to the high Andes of Bolivia. The plant was discovered by Karel Kníže in 1969 at an elevation of 4,000 m (13,000 ft) near Otavi, in Potosí Department, Bolivia. However, it was not formally described until 1996 by Jan Říha. The genus is named after the town of Cinti in Chuquisaca Department.
