CULTIVATED plants which, either for their usefulness or their beauty,'have been to some considerable extent, and not merely as objects of curiosity, Cultivated by man—belong to natural orders widely different from each other, and scat tered throughout almost all parts of the vegetable kingdom.' The prevalence of partiCular qualities in particular natural orders, indeed, causes us to find groups of C. P. in some of them, as the cerealia or corn-plants among grasses; but with these arc botanically associated other species—usually far more numerous—to which no great value has ever keen attached, or which are objects of interest to the botanist alone. It may be that, iu some instances, the original preference of certain 'species was accidental, and that their ?present superiority over certain others is merely owing to the improvements effected by Cultivatibn; but we are no more entitled to assume that this has been ordinarily the ease, than that man has in his selection exhausted, or nearly exhausted, the resources nature,. Some plants are known to have been cultivated from the most remote his tone ages; some have but recently become the objects of human care, which yet are deservedly esteemed; and, in some instances—e.g., sea-kale—these have not been intro duced from regions newly explored, but are natives of the very countries which • have been the scats of ancient civilization. Probably, in the earliest ages, plants useful for fOod. alone were cultivated, and of these only a few kinds, as is still the case among savage 'tribes; it may perhaps be doubted whether plants yielding for clothing and cordage, or plants from which alcoholic beverages or narcotics could be procured, were, most likely next to engage attention.-Of C. P., plants affording articles of human food, are certainly the most important, as well as the most numerous class. See Foot). Next, to these may be ranked plants yielding fiber (q.v.). Other important classes of C."Th. are those yelding alcoholic beverages, all of which, however, are also to be ranked, among the plants yielding food. (see FERMENTED Liquons); those yielding tea, coffeeit cocoa, and other similar beverages, containing (q.v.), or some analogous print ciple; those yielding narcotics (q.v.), as tobacco and opium, sonic of which are and, some are not cultivated also for other purposes; those yielding dye-stuffs (q.v.);, thpsc yielding medicines (see OFFICINAL PLANTS); those yielding fixed oils (see OILS), seine of which are to be reckoned among plants valuable for food, on account of the use of their oils as articles of food, whilst they are also valuable on other accounts; those, yielding fodder (q.v.) for cattle; those yielding timber (see TIMBER TREES); those) employed for hedges (q.v.), etc. There are also many miscellaneous useful product of plants, and useful purposes to which they are applicable. Among the former are resins,, turpentines, essential oils, gum caoutchoue, gutta-percha, bark for tanning, etc.; arhong
the latter, the thatching of roofs, basket-making, and the supply of fpod necessary- for useful insects, which leads to the cultivation of the white mulberry da the food of the silkworm, and of the cochineal cactus or nopal as the food of the cochineal inset. Many plants highly valued for their usefulness are still scarcely or not at all cultivated: this is the ease particularly with many that yield medicines, for which the whole demlind is not too great to be easily suppliedby the plants growing wild, and with timber. trees,: the plantation of which only takes place in countries of very advanced civilization! The number of plants cultivated for their usefulness is continually increasing, as well as of those cultivated for their beauty. The cultivation of flowers and ornamental shrubs and trees, although unquestionably less ancient than that of some of the plants most necessary for the supply of urgent wants, nevertheless dates from a reitionj antiquity, and has always existed in every country entitled in any measure to the credit of civilization. Some C. P. have from a very early period been very widely diffused, as has particularly been the case with some of the corn-plants; but others have been con lined to particular regions through no necessity of climatic adaptation, but rather front want of intercourse among nations. Thus, seine of the finest ornaments of our green= houses and gardens, recently introduced into Europe, have been diligently cultiVated from time immemorial in China and Japan, in which countries also many"useful plants are cultivated still almost unknown in other parts of the world. The cultivation of useful aquatic plants is practiced in China to a degree unupproached in any other country.
The changes produced by cultivation present an interesting and difficult subject to the student of vegetable physiology. Increase of luxuriance and size is a result which might have been expected from abundant nutriment and favorable circumstances of growth; but the determination of the strength of the plant in its vegetation to particular parts, and their greater proportionate increase, is a more remarkable phenomenon', although of common occurrence, as is also the considerable modification of juices and qualities. To these effects of cultivation, perpetuated iu the progeny of the plants, and increased from one generation to another, we owe many of the most useful varieties of cultivated plants. Our cabbages, turnips, carrots, etc., differ very much from the wild plants of the same species; there is little, for example, that is eatable or nutritious in the root of a wild turnip, and the acridity occasionally to be observed even in cultivation exists in it to a much greater degree. Wild celery is poisonous, or almost so. How far the effects of cultivation can be extended, is a question not yet decided in general, nor with reference to particular species.