Page:Encyclopædia Britannica, Ninth Edition, v. 12.djvu/248

236 236 HORTICULTURE [PROPAGATION. filled compactly with suitable porous earth, the opening at the slit being stopped by pieces of slate or tile. The earth must be kept moist, which is perhaps best done by a thick mulching of moss, the moss being also bound closely over the openings in the vessel, and all being kept damp by frequent syringings. Reid remarks of this method of propagation that lie has effected it with clay and cow dung, well mixed, after the bark had been taken off all round, and wrapped about with a double or triple swaddling of straw or hay ropes (Scots Gardener, 1721). This process is sometimes found very useful in the case of choice conservatory plants which may be getting too tall for the house, such as a fine Draccena (fig. 53) or Yucca. Such a plant may be operated on wherever the stem has become firm and woody ; the top will not fail to make a fine young specimen plant, which might he removed in the course of about twelve months, while other shoots would no doubt be obtained from the old stem, which, with its head thus reduced, might be removed to quarters where it would not be an eyesore. The head would perhaps require steadying if the stem were loaded with a pot or box of soil, as at a in the figure. Mr Bain records (Paxt. May. Bot., xvi. 46) a successful experiment of this kind with a Draccena Draco which was getting too tall for its position. An incision was made in the stem half an inch deep to the extent of half its circumference, lime being applied to the wound to dry up the sap. This incision was from time to time deepened (and lime- dried) until severed, the top being suspended from the roof. After some months roots were protruded from between the woody structure and its bush-like covering, and the gigantic cutting was lowered into its place, and grew away freely. In this case Mr Bain was of opinion that success was due to the slowness of the process and the precautions taken to dry and harden the stem. (10) .By Grafts. Grafting is so extensively resorted to that it is impossible here to notice all its phases. It is perhaps of most importance as the principal means of propagating our hardy kinds of fruit, especially the apple and the pear ; but the process is the same with most other fruits and ornamental hardy trees and shrubs that are thus propagated. The stocks are commonly divided into 3. two classes : (1) free stocks, which consist of seedling plants, chiefly of the same genus or species as the trees from which the scions are taken ; and (2) dwarfing stocks, which are of more diminutive growth, either varieties of the same species or species of the same or some allied genus as the scion, which have a tend ency to lessen the expansion of the engrafted tree. The French Paradise is the best dwarfing stock for apples, and the quince for pears. In determining the choice of stocks, the nature of the soil in which the grafted trees are to grow should have full weight. In a soil, for example, naturally moist, it is proper to graft pears on the quince, because this plant not only thrives in such a soil, but serves to check the luxuriance thereby produced. The scions should always be portions of the wood of the preceding year, selected from healthy parents ; in the case of shy-bearing kinds, it is better to obtain them from the fruitful branches. The scions should be taken off some weeks before they are wanted, and half- buried in the earth, since the stock at the time of grafting should in point of vegetation be somewhat in advance of the graft. During winter, grafts may be conveyed long distances, if carefully packed. If they have been six weeks or two months separated from the parent plant, they should be grafted low on the stock, and the earth should be ridged up round them, leaving only one bud of the scion ex posed above ground. The best season for grafting apples and similar hardy subjects is the month of March; but it may be commenced as soon as the sap in the stock is fairly in motion, and may be con tinued during the first half of April. Whip-grafting or Tongue-grafting (fig. 54) is the most usual mode of performing the operation. The stock is headed off by an oblique transverse cut as shown at a, a slice is then pared off the side as at b, and on the face of this a tongue or notch is made, the cut being in a downward direction ; the scion c is pared off in a similar way by a single clean sharp cut, and this is notched or tongued in the opposite direction as the figure indicates ; the two are then fitted together as shown at d, so that the inner baik of each may come in contact at least on one side, and then tied round with damp soft bast as at c ; next some grafting clay is taken on the forefinger and FIG. 54. Whip-Grafting or Tongue- Grafting. pushed down on each side so as to fill out the space between the top of the stock and the graft, and a portion is also rubbed over the ligatures on the tide where the graft is placed, a handful of the clay is then taken, flattened out, and rolled closely round the whole point of junction, being finished off to a tapering form both above and below, as shown by the dotted line/. To do this deftly, the hands should be plunged from time to time in dry ashes, to prevent the clay from sticking to them. Cleft-grafting (fig. 55) is another method in common use. The stock a is cleft down from the horizontal cut d, and the scion, when cut to a thin wedge form, as shown at c and c, is inserted into the cleft ; the whole is then bound up and clayed as in the former case. This is not so good a plan as whip-grafting ; it is improved by sloping the stock on one side to the size of the graft. FIG. 55. Cleft-Grafti FIG. 50. Crown-Grafting. Crown-grafting or Rind- graft ing (fig. 56) is preferable to cleft- grafting, inasmuch as it leaves no open spaces in the wood. The stock b is cut off horizontally or nearly so, and a slit is then cut in the bark/,/, a wedge-shaped piece of ivory being inserted to raise the bark ; the scion is then cut to the same wedge-shaped form &amp;lt;], h, and inserted in the space opened for it between the albumen and the bark, after which it is tied down and clayed over in the manner already described. Side-grafting is performed like whip-grafting, the graft being inserted on the side of a branch and not at the cut end of the stock. It may be practised for the purpose of changing a part of the tree, and is sometimes very useful for filling out vacant spaces, in trained trees especially. Inarching is another form of side-grafting. Here the graft is fixed to the side of the stock, which is planted or potted close to the plant to be worked. The branches are applied to the stock while yet attached to the parent tree, and remain so until united. In the case of trained trees, a young shoot is sometimes inarched to its parent stem to supply a branch where one has not been developed in the ordinary way. For the propagation by grafts of stove and greenhouse plants the process adopted is whip-grafting or a modification of it. The parts