CHAPTER X.

OF PROPAGATION BY CUTTINGS.

THIS, which is the most common of all modes of artificial propagation except grafting, depends upon essentially the same principle as propagation by eyes; that is to say, the pieces of a plant called cuttings possess a power of growth in consequence of their bearing leaf-buds or eyes upon their surface. In striking by eyes, we have the great difficulty to encounter of keeping the eye active till it has organized roots with which to feed itself; the earth furnishes such a supply unwillingly or unsuitably, nature intending that the bud should, in the first instance, be supported by the soluble nutriment ready prepared and lodged in its immediate vicinity, in the pith or some other part of the stem. For this reason, cuttings, which consist of eyes and the part containing their proper aliment, usually strike root more freely than eyes by themselves.

This being so, it is plain that a cutting is only capable of multiplying a plant when it bears buds upon its surface; and as the stem is the only part upon which buds certainly exist, so the stem is the only part from which cuttings should be prepared. And again, as the internode, or that space of the stem which intervenes between leaf and leaf, has no buds, their station being confined to the axil of the leaves, a cutting prepared from an internode only is as improper as one from the root. It is no doubt true, that we constantly propagate plants from pieces of what are called roots, as in the Potato, or the Scirpus tuberosus; but such roots are, in reality, the kind of stem called a tuber, and, in like manner, other cases of

282

CUTTINGS FROM ROOTS.

similar propagation are also successful, because the part called a root is, in reality, an underground stem covered with the rudiments of leaves, to each of which an eye belongs. The Rose, the Lilac, and many other plants have subterranean stems, cuttings of which will therefore answer the purpose of propagation. It also occasionally happens, that, owing to unknown causes, morsels of the true root will generate what are called adventitious buds; and hence we do occasionally see the root employed for propagation, as in Cydonia japonica, Anemone japonica, &c., but these are exceptional cases, and do not affect the general rule.

Since, however, there are many such cases, the propagator will do well to try roots whenever a plant refuses to strike by ordinary methods. Where unexpected difficulty is found to exist, the best way of proceeding is to place the cuttings of roots on damp sand, pressed half way into it, covered close with a bell-glass, exposed to moderate light, and kept at a temperature of from 60° to 65°. There is every reason to believe that moderate light contributes greatly to the excitement of vital action, and consequently to the formation of buds.

Monsieur Neumann in his very useful treatise on propagation gives several examples of root-striking, from among which the following may be selected. Dais cotinifolia propagates readily by its roots cut into

pieces and laid on earth in a hothouse, although its branches strike most unwillingly. In like manner, in the case of Paulownia imperialis, portions of the roots from to of an inch in diameter, and from 1 to 2 inch long, root well. The month of March is the most favourable time for striking these cuttings; for in February they often rot. The

CUTTINGS FROM ROOTS.

283

shoots of this plant, struck from root cuttings, come out round the root as is seen in Fig. XL., n; this gives the means of splitting the roots into several pieces, which, separately, strike as well as an entire root, Fig. XL., o. In Maclura aurantiaca, Fig. XLI., roots are formed between the wood

Fig. XLI.-Root-cutting of Maclura aurantiaca.

and the bark by an innumerable number of exceedingly minute bulbs, which turn green and produce buds. Cuttings of this plant strike easily in the open air. In Cydonia japonica, if we cut the roots the size of a pen into pieces 2 or 2 inches long, and plant them upright, we shall have the same year as many plants as there were pieces planted. These cuttings should be made in the open air, along a border or strip of peat, without any other covering than the soil where they are to grow. If we plant them vertically, we should cover them very slightly with earth; and at the first watering the cut will be uncovered. If we place them horizontally, they should be covered with earth about of an inch deep. This last method succeeds equally well, but it is less certain than the first. Mons. Neumann's experience has also showed that even Conifers may be struck from pieces of the root, concerning which he makes the following statement. During six years he had many times tried to strike an Araucaria from cuttings of the roots, but without success; at last, on the 10th May, 1844, he perceived that the cuttings of the roots of Araucaria Cunninghami, inch in diameter, and about 2 to 3 inches long, planted in October, 1843, were sending forth shoots. He attributes his failure, up to this time, to the presence of the glasses with which he covered the cuttings: the constant presence of air charged with an excess of moisture making them perish. In the first place, the pots which contained the roots were, in October, plunged into tan still gently warm; perceiving in March that the earth in the pots was decomposed, he changed it, without being able to distinguish the least sign of vegetation on the cuttings. The pots were then placed upon a bench

284

STEMS ROOT IN AIR.

and exposed to a moderate temperature; in April these pots were placed upon a warm bed of tan; and it was this, doubtless, which, a month afterwards, excited vegetation. He expresses his opinion that all Conifers may be multiplied in a similar manner if root cuttings are employed in Spring. This opinion is not, however, generally entertained by others.

When the Vine grows in a very warm damp stove, its stem emits roots into the air; the same thing happens to the Maize on the lower part of its stem; and in these and all such cases, the roots are found to be emitted from buds. Hence it has been inferred that the roots of a plant are as much productions of buds as branches are, and that the stem is nothing more than a collection of such roots held together under the form of wood and bark. The present is not the place for a renewal of this discussion, for the arguments in favour of and opposed to which, the reader is referred to my Introduction to Botany, 3d edit. p. 309, &c. It is sufficient here to remark, that the question turns upon whether the buds and leaves actually themselves produce roots, or merely furnish the organizable matter out of which roots are formed; and that, therefore, for the purpose of horticulture, either one or the other is equally capable of explaining the facts connected with cuttings.*

As far as physiology can explain the operation of propa

*The following curious fact, recorded by Mr. Livingstone, which seems to have escaped observation, deserves to be mentioned here;-"The Pterocarpus Marsupium, one of the most beautiful of the large trees of the East Indies, and which grows in the greatest perfection about Malacca, affording, by its elegant wide-expanding boughs, and thick-spreading pinnated leaves, a shade equally delightful with the far-famed Tamarind tree, is readily propagated by cuttings of all sizes, if planted even after the pieces have been cut for many months, notwithstanding they appear quite dry, and fit only for the fire. I have witnessed some of three, four, five, six, and seven inches in diameter, and ten or twelve feet long, come to be fine trees in a few years. While watching the transformation of the log into the tree, I have been able to trace the progress of the radicles from the buds, which began to shoot from the upper part of the stump a few days after it had been placed in the ground, and marked their progress till they reached the earth. By elevating the bark, minute fibres are seen to descend contemporaneously as the bud shoots into a branch. In a few weeks these are seen to interlace each other. In less than two years the living fibrous system is complete; in five years no vestige of its log origin can be perceived; its diameter and height are doubled, and the tree is in all respects as elegant and beautiful as if it had been produced from seed." (Hort. Trans., iv. 226.)

CONDITIONS NECESSARY TO A CUTTING.

285

gation by cuttings, it appears that roots are formed by the action of leaves; that branches are developed from the buds; and that the buds are maintained by the suitable aliment stored up in the stem. Everything beyond this seems to be connected with specific constitutional powers, of which science can give no explanation.

In considering what conditions are most favourable to the maintenance of a cutting in the state required, in order to enable it to become a young plant, it will be most convenient, in the first place, to examine the rationale of some one method which is known to be successful. For this purpose, the following detail, by Mr. Knight, of his mode of striking the Mulberry, is selected:

"A considerable number of cuttings were taken from the most vigorous bearing branches of a Mulberry-tree, in the middle of November, 1812, and were immediately reduced to the length adapted to small pots, in which I proposed them ultimately to be planted, and which were between four and five inches deep. Each cutting was composed of about two parts of two-years-old wood, that is, wood of the preceding year, and about one third of yearling wood, the produce of the preceding summer; and the bottom of each was cut so much aslope, that its surface might be nearly parallel with that of the bottom of the pot in which it was to be placed.

"The cuttings were then inserted in the common ground, under a south wall, and so deeply immersed in it that one bud only remained visible above its surface, and in this situation they remained till April. At this period the buds were much swollen, and the upper ends of the cuttings appeared similar to those of branches which had been shortened in the preceding autumn, and become incapable of transmitting any portion of the ascending fluid. The bark at the lower ends had also begun to emit those processes which usually precede the production of roots. The cuttings were now removed to the pots to which they had been previously fitted, and placed in a moderate hot-bed; a single bud only of each cutting remained visible above the mould, and that being partially covered; and in this situation they vegetated with so much vigour, and