The appearance and peculiar shape of cacti invariably arouse great interest. They belong to a very large group of drought-resistant plants called succulents, capable of storing water in stems, leaves or roots. In the case of cacti, we deal mainly with stem succulents, therefore their stems are clearly thickened. The shape of cacti can vary. They include perfectly spherical forms, as well as plants with raised shoots. They can climb straight up, without branching (the so-called pillar forms) or, by branching, form candelabra, woody or shrubs. Interesting, little associated with cacti are forms with slender stems.Often these are epiphytes that grow in the crowns of trees, from where shoots hang freely. Their shoots, as a rule, are segmented. The best known genera from this group are, for example, Rhipsalis, Epiphyllum and Schlumberger logs, i.e. Christmas cactus. An interesting phenomenon are the shoot anomalies found among cacti, e.g. in the mutants of Gymnocalycium mihanovichii deprived of chlorophyll. Instead of the typical green color, they are colored yellow, pink or red. They cannot live independently, so they are grafted onto rootstocks. Another peculiarity is the crested forms, e.g. in the genus Notocactus.
In addition to storing water in the stems, cacti show a number of other adaptations to prolonged periods of drought. ). Typical leaves can also be found in genera that are not very advanced in terms of evolution, such as the Pereskia tree. In other genera, the leaves are replaced by thorns, which can be an unusual decoration.The thorns can be as long as 10 cm. There are various modifications - they can be frizzy (so-called paper or parchment), hair-like, comb-like or feathery, reminiscent of feathers. A special type of thorns are the so-called glochids, i.e. short, small thorns equipped with hooks, typical for example for prickly pears. They work like miniature harpoons - they break off easily and stick to the epidermis, which is why they are very annoying. An additional attraction of the cacti is their characteristic, regularly ribbed surface. Usually the ribs are straight, ie run vertically downwards from the top of the plant, but are sometimes twisted in a spiral. Their number may vary depending on the taxon. In Astrophyllum, there may be 5 or even 4 ribs, while in the genus Stenocactus their number exceeds 100 (up to 120). The genus Mammillaria has warts instead of ribs. At the tops of the ribs and nipples there are so-called areoles, i.e. places covered with down, from which grow a few thorns, and later also flowers - a great reward for proper care and patience.In most cacti, flowers appear only in those individuals that have reached the size specified for the species. Since cacti tend to grow slowly, it can take many years to see flowers. Cactus flowers have a unique structure. They look like shoots. They develop on clear, scaly tubes, often containing chlorophyll. The more evolutionarily advanced a species is, the less noticeable are the characteristics of the momentum. Flowers can bloom during the day or only at night. They are often very impressive. One of the largest sizes, over 20 cm in diameter, reach the flowers of some species of the genus Selenicereus, e.g. S. grandiflorus, known as the queen of the night due to the flowering time. Flowers of other types are much smaller, but they delight with the richness of colors: from white and yellow, through red, pink, to purple and purple. Some people, e.g. Mammillaria and Rebutia, after flowering have fruits - red berries as decoration.
Apart from the epiphytic genus Rhipsalis ,which occurs naturally in Africa , the homeland of all other species is the American continents - from Canada to Patagonia and the Strait Magellan.Cacti are often used by the Indians in many ways. They provide fuel, building material, torches, and are often eaten. Food is, for example, fruits of many species, such as prickly pear and candied shoots. Plants are often planted in the form of rows, acting as a fence. Many species are easy to grow and do well in heated apartments, which is why they are also valued ornamental plants. They work great in the so-called succulent gardens, in which they are combined with other succulents, e.g. agaves, aloe, spurgeons, gasteria or haworcja. They go best with natural, clay, unglazed terracotta-colored dishes. Cacti, planted in colorful pots with clear geometric shapes, are also used in modern interiors. Plants, displayed as solitary specimens, attract attention. Species of considerable size are suitable for this purpose, e.g. the spherical Echinocactus grusonii, in nature growing up to 3 m in diameter, or the erected statuesque Cereus with an unusual surface.
