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.
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.
Pediocactus is a genus of cacti. The genus comprises between 6 and 11 species, depending upon the authority. Species of this genus are referred to as hedgehog cacti, though that name is also applied to plants from the genera Echinocereus and Echinopsis. Species may also be referred to as pincushion cacti, a common name which is also applied to other genera.
Thelocactus is a genus of flowering plants in the cactus family Cactaceae. Members of the genus are native to the arid lands of Central and Northern Mexico.
Pediocactus bradyi subsp. winkleri, commonly known as Winkler's cactus or Winkler's pincushion cactus, is a small cactus endemic to the state of Utah in the United States. It is known only from Emery and Wayne Counties.
Ferocactus wislizeni, the fishhook barrel cactus, also called Arizona barrel cactus, candy barrel cactus, and Southwestern barrel cactus, is a species of flowering plant in the cactus family Cactaceae, native to northern Mexico and the southern United States. It is a ball-shaped cactus eventually growing to a cylindrical shape, with spiny ribs and red or yellow flowers in summer.
Sclerocactus polyancistrus is a species of cactus known by several common names, including redspined fishhook cactus, Mojave fishhook cactus, pineapple cactus, and hermit cactus.
Sclerocactus brevihamatus is a species of cactus known by the common name shorthook fishhook cactus.
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.
Pediocactus sileri is a rare species of cactus known by the common names Siler's pincushion cactus and gypsum cactus. It is native to southwestern Utah and northwestern Arizona in the United States. It is limited to a specific type of soil, individuals are often spaced far apart, and the species is threatened by a number of human activities such as off-road vehicle use, poaching, and uranium mining. This is a federally listed threatened species of the United States.
Pediocactus bradyi is a very rare species of cactus known by the common names Brady's pincushion cactus, Brady's hedgehog cactus, and Marble Canyon cactus. It is endemic to Arizona in the US, where it is restricted to Marble Canyon in Coconino County, though its exact distribution is not generally advertised due to poaching concerns. It is limited to a specific type of soil, it has a small distribution, and the species is threatened by a number of human activities. This has been a federally listed endangered species of the United States since 1979.
Pediocactus bradyi subsp. despainii is a rare species of cactus known by the common names Despain's cactus and San Rafael cactus.
Pediocactus knowltonii is a rare species of cactus known by the common names Knowlton's miniature cactus, Knowlton's pincushion cactus, and Knowlton's minute cactus.
Pediocactus peeblesianus is a rare species of cactus known by the common names Navajo pincushion cactus. It is endemic to the state of Arizona in the United States. The species is named after the Arizona botanist Robert Hibbs Peebles.
Sclerocactus brevispinus is a rare species of cactus known by the common name Pariette cactus. It is endemic to Utah in the United States, where it is known only from the Pariette Draw, a draw in Duchesne County. It is threatened by a number of processes and human activities.
Sclerocactus glaucus is a rare species of cactus known by the common name Colorado hookless cactus. It is endemic to Colorado in the United States, where it is known only from the area between Grand Junction and Montrose. It is a federally listed threatened species.
Sclerocactus wetlandicus is a rare species of cactus known by the common name Uinta Basin hookless cactus. It is endemic to Utah in the United States, where it is known only from the Uinta Basin. It may also be called the Pariette cactus, but this name is more appropriate for Sclerocactus brevispinus, the species endemic to the Pariette Draw of Duchesne County.
Sclerocactus papyracanthus is a species of cactus known by the common names paperspine fishhook cactus, grama grass cactus, paper-spined cactus, and toumeya. It is native to North America, where it occurs from Arizona to New Mexico to Texas and into Chihuahua, Northeastern Mexico.
Sclerocactus sileri, the Siler fishhook cactus, is a rare and very small cactus found mostly in mineral-rich desert areas of intermediate elevations, notably in the American states of Utah, Nevada, and northern Arizona.
Pediocactus simpsonii, known by the common names mountain cactus, snowball cactus, and mountain ball cactus, is a relatively common cactus that has adapted to survive in cold and dry environments in high elevation areas of the western United States. It can be found at higher elevations than any other cactus in North America. While not a landscape dominating plant, it is a relatively common species and the most common member of the genus Pediocactus. Because of its beauty and adaptation to cold environments it is sometimes grown by gardeners in areas that have few other choices due to the limited number of cactuses with cold adaptations. Like many cactuses its populations are sometimes threatened by this desirability due to the theft or removal of plants from the wild by collectors.
