CACTUS, in botany, a genus of the Icosandria Monogynia class and order. Natural order of Succulentx. Cacti, Jus sieu. Essential character : calyx one leafed, superior, imbricate ; corolla mani fold ; berry one-celled, many-seeded. There are twenty-seven species. This genus consists of succulent plants, per.
manent in duration, singular and variou% in structure ; generally without leaves, having the stem or branches jointed ; for the most part armed with spines in bun. dles, with which, in many species, bris tles are intermixed. The bundles of spines are placed on the top of the tu bercles in the C. mammillaris, smaller melon thistle, which is tubercled all over, and produces its flowers between the tubercles. In C. melocactus, great melon thistle, or turk's cap, the spines are rang ed in a single row on the ridge of the ribs : when it is cut through the middle, the inside is found to be a soft, green, fleshy, substance, very full of moisture. The flowers and fruit are produced in circles round the upper part of the cap. C. pitajaya, torch thistle, or torch wood, is upright, and grows to the height of eight or ten feet. The flower is whitish, very' handsome, but has scarcely any smell ; it is half a foot in diameter, and blows in the night. The fruit is of the
form and size of a hen's egg, of a shining scarlet colour on the outside ; the pulp is white, fleshy, sweet, eatable, full of small black seeds. C. grandiflorus, great flowering creeping cereus ; and C. fla gelliformis, pink flowering creeping ce reus, are the same with those already mentioned, except that the stems are weak, and cannot support themselves; they therefore seek assistance, and throw out roots from the stem like ivy. C. mo niliformis, necklace Indian fig ; the branches are jointed, and very much flat ted; the bundles of spines or bristles are scattered over the surface, and the flow ers are produced from the edge of the branches. C. phyllanthus, spleenwort leaved Indian fig, has the branches much thinner, and may be fairly denominated leaves ; they are indented along the edge, and the flowers come out singly from the indentures. The fruit in some of the sorts is small, like currants, but in most it is large, and shaped like a fig; whence their name of Indian fig. These singular plants are all natives of the continent of South America and the West Indian. islands.