CACTACEIE, or CACTEiE, Indian Figs, the Cactus Tribe, a natural order of Exogenous plants.
The fructification of these plants consists of a calyx adhering to the • ovary, with a border divided into an uncertain number of segments, which are arranged lu several rows, the one overlapping the other, and the innermost gradually ceasing to be green and leafy, but acquiring the delicacy and colour of petals. The latter usually pass into sepals by insensible gradations, aro very numerous', and often brilliantly coloured. The stamens originate in the orifice of the tube formed by the combination of the petals and sepals, are very nun:c row, and consist of delicate thread-shaped filaments terminated by small roundish anthers. The ovary, which, in consequence of its adhesion to the sepals, seems to occupy the places of the stalk of the flower, consists of a single cell lined with parietal placenta: covered over with minute ovules ; its style is slender ; the stigma is star shaped and divided into as many narrow lobes as the ovary contains placent--e. The fruit is a succulent berry, marked at the end by a broad scar formed by the separation of the limb of the calyx : it contains a great quantity of seeds, which consist of nothing but a skin containing a succulent embryo slightly two-lobed at the upper end.
In natural affinity these plants have been considered allied to the Gooseberry Tribe (Grossulacca') on account of the great similarity in the structure of their fruit, and in the general production of spines upon their branches. Their relationship is probably far greater with Matembryacew and the other epigyuous orders of polypetalous dicotyledons.
The habit of Ortetaeus is remarkable. They have a very succulent stem in which the woody system is developed in but a small propor tion compared to the whole mass. Usually the stem is angular or deeply channeled, occasionally it is destitute of both angles and channels, but in that ease is mostly either much compressed as in Opuntia, or leafy as in 1.'piphyllam. Sometimes it is cos:tit:now from the base to the apex, but in many instances it is divided off into regular joints, each of which has a similar form varying with the species : in these instances however it is worthy of remark that as the stems advance in age the angles fill up, or the articulations dis appear in consequence of the slow growth of the woody axis and the gradual development of the cellular substance ; so that "at the end of a number of years, which vary according to the species, all the branches of Cactacere, however angular or compressed they originally may have been, become trunks that are either perfectly cylindrical or which have scarcely any visible angles. This metamorphosis is one of the causes which render it so difficult to identify species that have been described in their native localities from full-grown speci mens with such as are cultivated in the gardens of Europe." The
greater part of the species have stems which are more or less elongated, but in some they are spherical, as in the whole genera Melocactus and Echinocactus. Whatever may be the form of the stem, they usually bear upon their surface little tubercles which at an early age lose the leaves. Those organs hOwever rapidly fall away, and are succeeded by tufts of hairs or spines hooked backward at the ends, and then the species have the appearance of being perfectly leafless.
All the species are believed to be natives of America, whence how ever some of the Opuntias have been so long introduced to the Old World that they have here and there taken possession of the soil, and appear like aboriginal inhabitants. Such is the case on the volcanic soil of /Etna, and in various places on the shores of the Mediterranean; and this has led to the erroneous idea entertained by Sprengel and others, that the Opuntia of Theophrastus was the Opuntia t•ulgaris of modern botanists. The Cactacece are chiefly found in the tropical parts of America, a few species only escaping from those countries ; as, for example, to the southern states of North America and to the highlands of Chili and Mendoza. They principally occur on hot dry rocks or plains where the commoner forms of vegetation could not exist, and may be considered one of the means which nature has provided for the support of man in regions where neither food nor water can be procured. Their stems are filled with an abundant insipid wholesome fluid, and their fruit is succulent and in many eases superior to that of European gooseberries. In the fevers of their native countries they are freely administered as a cooling drink, and being bruised they are eateemed a valuable means of curing ulcers. For the sake of such their uses, because of their rapid growth, and especially on account of the numerous spines with which they are armed, the Opuntias or Tunas, as the Spanish Americans call them, are much planted round houses as fences, which neither man nor animals can easily break through. They are not unfrequent in the dry forest lands of Brazil, but are said never to occur in the damper parts of the country. In stature they vary greatly, many of them having small creeping stems, which seem to crawl upon the ground among the dead branches of the surrounding trees, with whose gray colour their deep green shoots form a singular contrast. Others rise like candelabra with many angular ascending arms, while a few elevate their tall and deeply-channeled leafless trunks far above the stunted vegetation of the sterile regions they inhabit, reaching sometimes the height of 30 or 40 feet.