Cactus SVG – a family of perennial flowering plants of the order of cloves and flowers, includes about 127 genera and about 1750 species inhabiting mainly dry areas, including one of the driest deserts in the world – the Atacama Desert.
Prior to C. Linnaeus, the name Cactus SVG was not used for cacti, but only as part of the name Echinomelocactus. Under this name, M. Lobel and P. Peña (1570-1571) gave an illustration of the plant, which today is referred to as a melokaktus. At the end of the 16th and beginning of the 17th centuries, Tabernemontanus called it Melocarduus. Turnefort (1719) shortened the name Echinomelocactus to Melocactus, and designated all cactuses except for punctures. He gave an excellent illustration of the melokaktus, which Linnaeus quoted in the description of the genus Cactus (1754); he also quoted it in earlier editions of Genera Plantarum, beginning in 1737.
Almost all cactuses are highly specialized stem succulents with reduced leaves, adapted to water storage and conservation. The variety of the structure and size of the shoots, their growth directions and the nature of their branching caused the existence of analogues of almost all life forms (soft-barrelled trees and shrubs, vines, epiphytes and geophytes), as well as specific “cactus” forms of growth: single-spotted spherical and column-shaped. The largest cactuses reach a height of almost 20 meters (Carnegiea gigantea, Pachycereus pringlei), and the smallest ones are representatives of the genus Blossfeldia with spherical shoots of about 1 cm in diameter. Most succulent cactus species have the smallest evaporating surface per unit of water storage tissue. Most cactus leaves are missing, and the photosynthesis function is performed by the stem. Shoots in the vast majority of species are perennial, except for Opuntia chaffeyi and species of the genus Pterocactus, which often die off at the end of the growing season. Leafness of species with developed leaves is spiral. A characteristic feature of cactus species is modified axillary buds – areolae, where thorns, homologous renal scales develop. Cactus flowers are more often solitary, some peregrine flowers are in inflorescences, mainly axillary flowers and inflorescences, while a few species have terminal flowers. In some species, flowers develop on specialized parts of shoots – cephalas. Flowers are predominantly obesity, actinomorphic or zygomorphic, almost always with a well-developed flower tube, with a spiral corolla-like perianth consisting of numerous and indistinctly differentiated members, of which the most external are often green. Stamps are numerous, which is explained by the cleavage of their initially smaller number, attached spirally or in groups to the perianth tube; anthers open longitudinally. The pestle is usually long, with 3-20 blades of stigma. The ovary is sometimes even more or less upper (Pereskia aculeata), but usually lower, resulting from overgrowth of its overgrown floral composition, which is proved by the characteristic bending and reverse course of conducting beams, presence of areola on the outer surface of the areola, cases of shoots formation on the lower ovary of some Cactus SVG. Seeds are numerous, on long seed-stems. Seeds with straight or more often bent embryo. Fruits are very diverse: berry-like (flesh is composed mainly of overgrown seedlings) licking or cracking, drying out with a weathered wall or opening due to improper rupture of the wall.
The main number of chromosomes in cactus x=11. Diploids 2n=22 prevail, there are polyploids (2n=33, 2n=44, 2n=55, 2n=66, 2n=77, 2n=88).
Cactus SVG – plants of the New World, their natural range – South America and North America, as well as the West Indies. The species Rhipsalis baccifera is found, apart from America, also in Africa, Madagascar and Sri Lanka, where it is believed to have been introduced as a human species. Seed introductions by migratory birds were also assumed, but there are no bird species that would make such migrations. The northernmost point of the natural range of the family is 56°17′ N, the northernmost cactus species is Opuntia fragilis, which grows along the Pis River in the Canadian provinces of British Columbia and Alberta. There is no consensus on the southernmost point and southernmost species. Some authors believe that this is Austrocactus patagonicus, found at 50°23′ S in Argentina, while others consider Maihueniopsis darwinii to be the southernmost species. The latter has a typical population of about 47° latitude. Jonkers’ (1998) report on the discovery of Maihuenia poeppigii in Chile, in the Torres del Payne National Park, about 1400 km south of the southernmost known population, is questionable. Man has introduced some cactus species, mostly pearl cacti, to all continents except Antarctica. The species Opuntia humifusa is distributed throughout the Mediterranean and is found on the coast of Crimea, the Russian Black Sea coast, near the cities of Gelendzhik and Novorossiysk, as well as in Tbilisi, near the botanical garden. The Kordon tract in the Astrakhan region has a population of Opuntia phaeacantha, the northernmost in Russia; wild pearls in the Sevastopol area and on the southern coast of Crimea live approximately 3° south.