GRAFTING. The operation of affix ing one portion of a plant to another, in such a manner as that vital union may take place between them. A graft con sists of two parts ; the stock or stein, which is a rooted plant, fixed in the ground, and the scion, a detached por tion of another plant, to be affixed to it. The operation of grafting can only be per formed within certain limits.
In general, all the species of one genus may be grafted on,one another recipro cally ; hut this is not universally the case, because the apple cannot be grafted on the pear, at least not for any useful pur pose. In general, it may be presumed that all the species of a natural order, or at least of a tribe, may be grafted on one another ; but this does not hold good uni versally. The reverse of this doctrine, however, that the species belonging to different natural orders cannot be grafted on one another holds almost universally true ; and therefore a safe practical con clusion is, that in choosing a stock, the nearer in affinity the species to which that stock belongs is to the scion, the more certain will be the success.
Grafting is one of the most important operations in horticulture, as affording the most eligible means of multiplying and perpetuating all our best varieties of fruit-trees, and many kinds of trees and shrubs not so conveniently propagated by other means. Varieties of fruits are on ginally procured by selection from plants raised from seed, but they can only be perpetuated by some mode which con tinues the individual ; and though this may be done by cuttings and layers, yet by far the most eligible mode is by graft ing, as it produces stronger plants in shorter time than any otherinethods.
Grafting is performed in a great many different ways, but the most eligible for ordinary purposes is what is com monly called spliced grafting or whip grafting. In executing this mode, both the scion and the stock are pared down in a slanting direction; afterward applied together, and made fast with strands of bast matting, in the same manner as two pieces of rod are spliced together to form a whip handle. To in sure success, it is essentially necessary that the elburnnm or inner bark of the scion should coincide accurately with the inner bark of the stock, because the vital union is effected by the sap of the stock rising up through the soft wood of the scion. After the scion is tied to the stock, the graft is said to be made ; and it only remains to cover the part tied with a mass of tempered clay, or any convenient composition that will exclude the air. The season for performing the operation is, for all deciduous trees and shrubs, the spring, immediately before the movement of the sap. The spring is also the most favorable season for ever greens ; but the sap in this class of plants being more in motion during winter than that of deciduous plants, grafting, if thought necessary, might be performed at that season.
Grafting by approae7z, or marching, is as mode of grafting, in which, to make sure of success, the scion is not separated from the parent plant till it has become united the stock. For this pur pose, the stock and the plant containing the scion must be growing close together; and the scion being drawn to one side, and made to approach the stock, is spliced to it by cutting off a portion of its bark and wood, and a similar portion of the hark and wood of the stock, applying the one to the other so that their alburnums may join, and then making both fast by matting, and excluding the air by clay, grafting wax, or moss. When the scion has effected a vital union with the stock, its lower extremity is cut through, so as to separate it from the parent plant, and it now becomes an independent graft. In this way trees of difficult propagation may be propagated with certainty ; while if any of the other modes of propagation, whether by cuttings or grafting, were adopted, a proportion of the cuttings or scions woula, in all probability, be lost.
Grafting herbaeeous plants differs in no thing from grafting such as are of a woody nature, excepting that the opera tion is performed when both stock and scion are in a state of vigorous growth. Grafting herbaceous plants is but little practised in England, and on the Conti nent chiefly as a matter of ainuscinent. The only useful purpose to which it has hitherto been applied, is that of grafting the finer kinds of dahlias on tubers of the. more common and vigorous growing sorts. In the Paris gardens the tomato is some times grafted on the potato, the cauli flower on the borecole, and one gourd on another, as matter of curiosity.
Grafting the herbaceous shoots of woody plants—the greffe herbace of the French —is scarcely known among English gar deners; but it has been extensively em ployed by French nurserymen, and even in some of the royal forests of France. The scions are formed of the points of growing shoots ; and the stocks are also the points of growing shoots cut or broken over an inch or two below the point, where the shoot is as brittle as as paragus. The operation is performed in the cleft manner : that is, by cutting the lower end of the scion in the form of a wedge, and inserting it in a cleft or slit made down the middle of the stock. The finer kinds of azalias, pines, and firs are propagated in this way in the French nurseries, and thousands of Finns fart tio have been so grafted on Pinus sylroes tres in the forest of Fontainebleau. At Hopetomi House, near Edinburgh, this mode of grafting has been successfully practised with Abies Smithi,ana, the stock being the common spruce fir.