It is often desirable to be able to bud or graft one variety of plant on another entirely different variety; and it is an interesting fact to know that the bud taken from one plant and inserted so that it grows in another, and is entirely sustained by the plant into which it has been budded, in no way changes its character. This fact is so well known to gardeners that they rarely think it necessary to mention it in writing on the subject, and many amateurs interested in horticultural matters have very confused notions on budding. To illustrate: if a leaf bud is taken from a white Rose, and inserted in the stem of a red Rose, all the branches that proceed from this bud, leaves or flowers, will be identical with the white Rose from which it was taken. Or if a leaf bud of the red Rose be inserted in the white, the same result would follow; it will be identical in all respects with the red variety. Or you may take a bud or graft from the sourest crab apple, and insert it into a branch of the sweetest apple tree you can find, and the shoot which grows from the crab apple bud will ever remain a crab, and will in no way be affected by the sweet apple stock on which it is growing. Or if the operation is reversed, and the sweet apple is budded or grafted on the sour, the result will be the same; its individuality will be in no way changed, it will be identical with the variety from which it was taken.
Still further to illustrate this matter of budding or grafting, you may take a rose-bush having any number of shoots, it makes no difference whether one or a hundred; on each shoot you may bud a distinct variety of Rose, of all the colors, forms or odors embraced in the Roses, and each one will hold its distinct characteristic of color, form, or fragrance, be it crimson, white, pink, or yellow in color, double or single in form, or of tea or other odor. Or you may take a young seedling apple tree, insert a bud of another into it, then after that bud has made a growth, bud still another variety into that, and so on as many as is desired, rub of all shoots in the stem that start below, and the variety last budded will hold its individuality unchanged, no matter though the Life-sustainiug sap flows through the cells of several different kinds. You may mark the space occupied by each of the varieties, and cut back to any particular variety, and the fruit that will be produced by that part, which will then be the top, will hold its character without change. What is true of roses and apples, is of course equally true of whatever plant that can be grafted or budded.
The stock does not in any manner affect the individuality of the graft, and I supposed that this was one of the generally accepted axioms of horticulture, but in a conversation not long ago with a gentleman whose opinion is entitled to consideration, I found him inclined to believe that there were some few exceptions to what was admitted to be a general law, and in support of his argument, he referred me for exceptions to Darwin's "Plants and Animals under Domestication." I have examined this work, and find only two cases wherein it is claimed that the graft is influenced by the stock, or the stock by the graft. The first is at page 457, Vol. 1, where "Prof. Caspary describes the case of a six-year-old white Moss Rose, which sent up several suckers, one of which was thorny and destitute of moss, exactly like those of the Provence Rose, (R. centifolia), another shoot bore both kinds of flowers, and in addition longitudinally striped flowers. As this white moss had been grafted on the Provence Rose, Prof. Caspary attributes the above changes to the influence of the stock, but from the facts already given, and from others to be given, bud variation with reversion is probably sufficient explanation"; and Darwin proceeds to give nearly a dozen cases of like variation where there was no grafting at all. A very marked case of this "bud variation" is at the present time existing in my own greenhouses. In a bed of about one hundred plants of the new tea-rose, "La Nankin," all made from the cuttings from one parent plant, we have had four distinct varieties. The original flower or bud has its base or lower half of a nankeen yellow color, while its upper half is pure white, the separate colors being clearly defined, yet among our plants from cuttings we have some flowers that are entirely of the nankeen color, without white; then again pure white with no nankeen, and on one shoot the flowers came of a light pink or blush shade. Now had Prof. Caspary a grafted plant of "La Nankin" playing these freaks, he no doubt would have concluded that it was the influence of the graft on the stock. There are other instances in grafting where an amalgamation of individualities apparently occurs; these cases are familiar to all horticulturists of much experience, and are also alluded to by Darwin in the work above 3 referred to. He gives a number of instances where the variegated Oleander grafted on the plain leaved variety as a stock, imparts the variegation to the stock, or where a yellow-leaved ash tree, grafted on the common green-leaved variety, produced a blotched or variegated variety. That most of the variegation in the foliage of plants, is due to disease, or at least some disturbance of the regular functions of the leaf, there is but little doubt, and it is therefore but an accidental condition of the individual. Where a variegated plant is budded or grafted upon a healthy subject, the disease is transmitted from the unhealthy bud or graft to the healthy stock in a manner somewhat analogous to innoculation of smallpox virus in man. The character or constitution of the individual is in no way affected in the one case more than in the other. Marked instances in which plain-leaved plants become variegated by being grafted with variegated cions, are afforded by the variegated Abutilons; but in all such cases it is simply the "blotching" or "disease" of the foliage that occurs, there is no change whatever in the coloring of the flowers or shape of the leaves, the individuality of these remains unchanged. That leaf variegation is indicative of disease, is manifest from another fact. It is quite a common thing to find a shoot sent out by the silver-leaved or variegated Geraniums that is pure white in stem and leaves, not a particle of green, or such golden variegated kinds of Geraniums as "Mrs. Pollock" will send out a pure yellow shoot; but all efforts to make plants of such shoots will fail; they may feebly root as cuttings, or they may be grafted on a green-leaved, healthy stock long enough to drag out a few weeks of existence, but the disease is here thoroughly established, and all attempts to propagate these entirely abnormal growths completely fail. It has been claimed that the Duchesse d'Angouleme and other pears are much better flavored when grafted on the quince than on the pear stock, and these are quoted as examples of the influence of the stock on the graft, but to me this seems capable of another explanation:
We know that the pear stock is a vigorous and rampant grower as compared with the quince, and may it not be that this vigor of growth in the tree impairs the flavor of the fruit in some varieties, just as we find the flavor of fruits impaired when grown in too rich soil? The effect of soil upon quality is particularly marked in melons. I remember that I once grew a field of three acres of nutmeg melons, one-half of the patch was rich bottom land, and the other portion was a rather poor hillside. The fruit produced on the bottom was much larger, but so different from and inferior in flavor to those on the hillside that no one would have recognized the two as being of the same variety. The same, though in a less marked degree, probably occurs in other fruits under similar conditions. From these reasons I believe it safe to assert that no evidence has yet been shown wherein the stock in any manner affects the graft other than that it may cause it to grow stronger or weaker, just as the stock is strong or weak, and the amount of such influence will be only such as a rich or poor soil would produce. In other words, the "stock" is only a medium or soil wherein the grafted individual grows, and affects it no more than if it drew its sustenance direct from the earth - strong, if on a strong stock, as on a fertile soil, and weak, if on a weak stock, as on a sterile soil.