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CACTUS
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CACTUS . This word, applied in the See also:form of KhKros by the See also:ancient Greeks to some prickly plant, was adopted by See also:Linnaeus as the name of a See also:group of curious succulent or fleshy-stemmed See also:plants, most of them prickly and leafless, some of which produce beautiful See also:flowers, and are now so popular in our gardens that the name has become See also:familiar. As applied by Linnaeus, the name Cactus is almost conterminous with what is now regarded as the natural See also:order Cactaceae, which embraces several See also:modern genera. It is one of the few Linnaean generic terms which have been entirely set aside by the names adopted for the modern divisions of the group. The Cacti may be described in See also:general terms as plants having a woody See also:axis, overlaid with thick masses of cellular See also:tissue forming the fleshy stems. These are extremely various in See also:character and form, being globose, cylindrical, columnar or flattened into leafy expansions or thick See also:joint-like divisions, the See also:surface being either ribbed like a See also:melon, or See also:developed into nipple-like protuberances, or variously angular, but in the greater number of the See also:species furnished copiously with tufts of horny spines, some of which are exceedingly keen and powerful. These tufts show the position of buds, of which, however, comparatively few are developed. The stems are in most cases leafless, using the See also:term in a popular sense; the leaves, if See also:present at all, being generally reduced to See also:minute scales. In one genus, however, Peireskia, the stems are less succulent, and the leaves, though rather fleshy, are developed in the usual form. The flowers are frequently large and showy, and are generally attractive from their high colouring. In one group, represented by Cereus, they consist of a See also:tube, more or less elongated, on the See also:outer surface of which, towards the See also:base, are developed small and at first inconspicuous scales, which gradually o-a 000 QU"~OOO- Opf000 t, See also:Flower reduced; 2, Same in See also:vertical See also:section; 3, Flattened See also:branch much reduced; 4, See also:Horizontal See also:plan of arrangement of flower. increase in See also:size upwards, and at length become crowded, numerous and petaloid, forming a See also:funnel-shaped blossom, the beauty of which is much enhanced by the multitude of conspicuous stamens which with the See also:pistil occupy the centre. In another group, represented by See also:Opuntia (fig. I), the flowers are rotate, that is to say, the See also:long tube is replaced by a very See also:short one. At the base of the tube, in both See also:groups, the ovary becomes developed into a fleshy (often edible) See also:fruit, that produced by the Opuntia being known as the prickly See also:pear or See also:Indian fig. - The See also:principal modern genera are grouped by the See also:differences in the flower - tube just explained. Those with long - tubed flowers comprise the genera See also:Melocactus, See also:Mammillaria, Echinocactus, Cereus, See also:Pilocereus, Echinopsis, See also:Phyllocactus, See also:Epiphyllum, &c.; while those with short-tubed flowers are See also:Rhipsalis, Opuntia, Peireskia, and one or two of See also:minor importance. Cactaceae belong almost entirely to the New See also:World; but some of the Opuntias have been so long distributed over certain parts of See also:Europe, especially on the shores of the Mediterranean and the volcanic See also:soil of See also:Italy, that they appear in some places to have taken See also:possession of the soil, and to be distinguished with difficulty from the aboriginal vegetation. The habitats which they affect are the hot, dry regions of tropical See also:America, the aridity of which they are enabled to withstand in consequence of the thickness of their skin and the paucity of evaporating pores or stomata with which they are furnished,—these conditions not permitting the moisture they contain to be carried off too rapidly; the thick925 fleshy stems and branches contain a See also:store of See also:water. The succulent fruits are not only edible but agreeable, and in fevers are freely administered as a cooling drink. The See also:Spanish Americans plant the Opuntias around their houses, where they serve as impenetrable fences. Additional information and CommentsThere are no comments yet for this article.
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