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.
Barrel cacti are various members of the two genera Echinocactus and Ferocactus, endemic to the deserts of Southwestern North America southward to north central Mexico. Some of the largest specimens are found in the Sonoran Desert.
Schlumbergera is a small genus of cacti with six to nine species found in the coastal mountains of south-eastern Brazil. These plants grow on trees or rocks in habitats that are generally shady with high humidity, and can be quite different in appearance from their desert-dwelling cousins. Most species of Schlumbergera have stems which resemble leaf-like pads joined one to the other and flowers which appear from areoles at the joints and tips of the stems. Two species have cylindrical stems more similar to other cacti.
Melocactus, also known as the Turk's cap cactus, or Pope's head cactus, is a genus of cactus with about 30–40 species. They are native to the Caribbean, western Mexico through Central America to northern South America, with some species along the Andes down to southern Peru, and a concentration of species in northeastern Brazil.
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.
Vatricania is a monotypic genus of flowering plants belonging to the family Cactaceae. It just contains one species, Vatricania guentheri(Kupper) Backeb.Greenm. ex Gleason It has the common name of Red Tail Cactus.
Echinocactus grusonii or Kroenleinia grusonii, popularly known as the golden barrel cactus, golden ball or mother-in-law's cushion, is a species of barrel cactus which is endemic to east-central Mexico.
The buffy hummingbird is a species of bird in the hummingbird family Trochilidae. It is the only species placed in the genus Leucippus. This bird lives in dry forest and scrubland in northern South America where it feeds on insects and the nectar, flesh, and juice of cactus fruits.
Melocactus azureus is a species of cactus. It is endemic to Brazil, where it is known only from Bahia. It is locally abundant but the populations are fragmented and vulnerable to habitat degradation.
Neobuxbaumia macrocephala is a long-lived columnar cactus
Euphorbia mammillaris is a plant species endemic to Cape Province of South Africa. Euphorbia mammillaris, also known as African or Indian corn-cob, is a fast-growing shrublet, with thick stems that are chalky green, erect and ribbed.
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.
Melocactus caroli-linnaei is a cactus found in Jamaica. When mature it is columnar, up to 1 m (3.3 ft) high. Like all species of Melocactus, it forms a "cephalium" when mature – a dense mass of areoles covered with wool and spines at the tip of the stem. Flowers are produced only from the cephalium.
Melocactus matanzanus, common name dwarf Turk's-cap cactus or Turk's-cap cactus, is a cactus in the genus Melocactus of the family Cactaceae. The epithet matanzanus is derived from the Cuban province of Matanzas.
Espostoa lanata is a species of cactus of the genus Espostoa.
Melocactus lemairei is a species of cactus endemic to the Caribbean island of Hispaniola. It is named after French botanist and cactus expert Charles Antoine Lemaire.
Melocactus neryi is a species of flowering plant from the genus Melocactus.
Melocactus ernesti is one of the Turk's cap cacti, and is native to Bahia and Minas Gerais States, Brazil.
The acitrón is a Mexican candy which is commonly used as a decoration on a three kings' cake. As an ingredient, it has great cultural significance since it is used in a large number of ritual and festive preparations. Unfortunately, the biznaga cactus from which acitróns are made is an endangered species due to excessive consumption.
Melocactus bahiensis is a species of Melocactus found in Bahia, Brazil.
Flowers emerge from cephalium of Arrojadoa penicillata .
Cephalium of Melocactus matanzanus
Lateral cephalium of Espostoa lanata
