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.
Matucana is a genus of cacti, containing approximately 20 species of mostly globular plants. The genus is only known from Peru, mostly along the Marañón River.
Hylocereus is a former genus of epiphytic cacti, often referred to as night-blooming cactus. Several species previously placed in the genus have large edible fruits, which are known as pitayas, pitahayas or dragonfruits. In 2017, a molecular phylogenetic study confirmed an earlier finding that the genus Hylocereus was nested within Selenicereus, so all the species of Hylocereus were transferred to Selenicereus.
Pseudorhipsalis is genus of cacti. This genus is often included in Disocactus. It is epiphytic, many branched, and elongated with flattened, serrated cladodes. In its early life, it stands erect, but soon becomes prostrate. It produces numerous flowers.
Hatiora is a small genus of epiphytic cacti which belongs to the tribe Rhipsalideae within the subfamily Cactoideae of the Cactaceae. Recent taxonomic studies have led to the three species formerly placed in subgenus Rhipsalidopsis being removed from the genus, including the well known and widely cultivated ornamental plants known as Easter cactus or Whitsun cactus.
Lymanbensonia is a genus of epiphytic cacti in the tribe Lymanbensonieae, found in Bolivia, Ecuador, and Peru. The genus was recently reinstated after it was found to be unrelated to Pfeiffera.
Rhipsalidopsis is a small genus of flowering plant in the family Cactaceae, native to southern Brazil. Like other members of the tribe Rhipsalideae, its species are epiphytes, growing on trees.
Discocactus is a genus of tropical cacti. Discocactus plants are endemic to southern Brazil, eastern Bolivia, and northern Paraguay. These species are in the risk of extinction in the wild.
Rhipsalis baccifera, commonly known as the mistletoe cactus, is an epiphytic cactus which originates from Central and South America, the Caribbean, and Florida. It is also found throughout the tropics of Africa and into Sri Lanka where it is known in Sinhala as nawahandi (නවහන්දි). This is the only cactus species naturally occurring outside the Americas. One hypothesis is that it was introduced to the Old World by migratory birds, long enough ago for the Old World populations to be regarded as distinct subspecies. An alternative hypothesis holds that the species initially crossed the Atlantic Ocean on European ships trading between South America and Africa, after which birds may have spread it more widely.
Aporocactus martianus is a species of cactus found in Oaxaca, Mexico.
Schlumbergera kautskyi is a species of plant in the family Cactaceae. It is endemic to a small area of the coastal mountains of south-eastern Brazil where its natural habitat is rocky areas. It is threatened by habitat loss. It is in the same genus as the popular houseplant known as Christmas cactus or Thanksgiving cactus.
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.
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.
The Hylocereeae are a tribe of cacti. Most are found in the tropical forests of Central and northern South America, and are climbers or epiphytes, unlike most cacti. The tribe includes between six and eight genera in different circumscriptions. The plants known as "epiphyllum hybrids" or "epiphyllums", widely grown for their flowers, are hybrids of species within this tribe, particularly Disocactus, Pseudorhipsalis and Selenicereus, less often Epiphyllum, in spite of the common name.
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.
Rhipsalidopsis rosea, synonyms Hatiora rosea and Schlumbergera rosea, is a species of flowering plant in the family Cactaceae, native to south Brazil. It was first described, as Rhipsalis rosea, by Gustaf Lagerheim in 1912. It is one of the parents of the hybrid Rhipsalidopsis × graeseri, grown as the Easter or Whitsun cactus.
Schlumbergera lutea, synonym Hatiora epiphylloides, is a species of flowering plant in the family Cactaceae, subfamily Cactoideae, native to southeast Brazil. It is a shrubby epiphyte, with flattened stems and bright yellow flowers.
Hatiora cylindrica is a species of often epiphytic cactus in the tribe Rhipsalideae within the subfamily Cactoideae. It is native to east Brazil, where it grows in a variety of habitats, including moist forest, dunes and coastal rocks.
Hatiora herminiae is a species of flowering plant in the tribe Rhipsalideae, family Cactaceae. It grows as an epiphyte in cloud forests in Southeast Brazil.
Strophocactus wittii, synonym Selenicereus wittii, known as the Amazon moonflower, is a species of plant in the genus Strophocactus in the cactus family (Cactaceae), and is one of several species commonly called "moonflowers". It was first described in 1900 and is one of three species of cactus found in the central Amazon basin.
