OF PLANTS DEPRIVED OF WATER, AND OF OTHERS.

261

"M. Bové, in his relation of a botanical journey in Egypt in 1829, says, 'in visiting the estate of Ibrahim Pacha, one of his directors pointed out, near the village of Kouba, a stock of a Locust-tree (Ceratonia siliqua), which he said had been planted about 300 years. The tree was cut down by the French, during their invasion; its roots remained in the earth, and gave no indications of vegetation till the Pacha caused the earth to be broken up about it in 1826, and a well to be sunk, the moisture from which induced it to throw up three branches, which in three years were three or four yards high, and almost 12 inches in circumference at the base. Even flower-buds seemed disposed to show themselves on the branches. Thus this stock remained buried for 30 years without perishing, and probably without ceasing to increase in size. This surprising fact may be placed by the side of that mentioned by M. Dutrochet of a kind of Pine, whose root year after year produced new layers of wood for 90 years, without any existence of a stem. M. Gaudichaud has also made known a remarkable instance of the duration of life in a shoot of Cissus hydrophora, which after being dried three years in a herbarium, and even after being placed in an oven, furnished cuttings, by which it has been propagated in the hothouses of the Museum of Natural History.

"I have noticed that fleshy roots, like those of Pæonies, do not produce tops when they are cut, except those of Chinese Pæonies. The same thing occurs with bulbous and fusiform roots, deprived of their buds or eyes, although others produce tops, although they have been cut into several pieces. There are perennial grasses whose roots are preserved for more than a year in the earth without emitting roots. The same takes place with the rhizomes of many Asters, Solidagos, Cinerarias, and Helianthuses, and a great number of other genera. Analogous facts are remarked among succulent plants, and such monocotyledons as Dracana, Arads, &c. I have had for eight years shoots of a Cereus peruvianus, which, in the free air of a room, left without water or earth, produced every year new roots about an eighth of an inch long, and were thus preserved for a year or two before they dried up. During the first three years these shoots grew an inch or more every year; for two years afterwards they lived, but did not grow. Many Cactus cuttings remain three or four years without any appearance of vegetation, although the pots in which they are planted are filled with roots. Shoots of Cactus phyllanthoides, under similar circumstances, every year formed a portion of a stem, at the extremity of the old one, and on these stems two flowers have been seen to blossom, after which the old shoot became yellow, then dried, became tough, and what had grown upon it gradually perished. I have also preserved without water shoots of Stapelia asterias, variegata, caespitosa, and hirsuta, and they have all produced flowers; and the same has happened with Aloes, which have lived for three or four years, producing new roots, and forming buds along their whole length."

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PROLONGED VITALITY OF PLANTS.

In conclusion, M. Pépin gives a list of plants, fragments of whose roots have remained buried and torpid for several years. The more remarkable are the following:—Bignonia radicans, 10 years; Gymnocladus canadensis, 10; Locust trees, 10; Ulmus campestris, 6; Dodartia orientalis, 8: Euphorbia dulcis, 6; Hoffmannseggia falcata, 10; Solanum carolinianum, 10; Pulmonaria virginica, 5; Urtica cannabina, 4. It is almost needless to add, that with plants like those mentioned by M. Pépin, very slender precautions suffice to insure their living through the longest voyages, if prepared in the manner adopted by Messrs. Loddiges, as already described, and that his statements sufficiently establish the fact that plants possess different powers of vitality, those of some being infinitely greater than what belongs to others.

CHAPTER VIII.

OF PROPAGATION BY EYES AND KNAURS.

THE power of propagating plants by any other means than that of seeds depends entirely upon the presence of leaf-buds (Fig. XXXIV.), or, as they are technically called, "eyes," which are in reality rudimentary branches in organic connection with the stem. All stems are furnished with such buds, which, although held together by a common system, have a power of

Fig. XXXIV.

independent existence under fitting circumstances; and, when called into growth, uniformly produce new parts, of exactly the same nature, with respect to each other, as that from which they originally sprang.

Under ordinary circumstances, an eye remains fixed upon the stem that generates it. There it grows, sending woody

264

PROPAGATION BY EYES.

matter downwards over the alburnum, and a new branch upwards, clothed with leaves, and perhaps flowers; but it occasionally happens that eyes separate spontaneously from their mother stem, and when they fall upon the ground they emit roots and become new plants (p. 44, Fig. X.). This happens in several kinds of Lily, and in other genera.

Man has taken advantage of this property, and discovered that the eyes of many plants, if separated artificially from the stem and placed in earth, will, under favourable circumstances, produce new plants, just as such eyes would have done if they had spontaneously disarticulated; hence the system of propagation by eyes, an operation employed only to a limited extent in actual practice, but which in theory seems applicable to all plants whatever. The species most generally so increased are the Potato and the Vine. Of the latter, the eye, with a small portion of the stem adhering to it, is commonly used as the means of obtaining young plants; being placed in earth, with a bottom heat of 75° or 80°, and kept in a damp atmosphere, it speedily shoots upwards into a branch, and at the same time establishes itself in the soil by the development of the requisite quantity of roots. In order to insure success in this operation upon the Vine, it is only necessary that the eye should be dormant, and that a small piece of well-ripened wood should, as has been already stated, be separated with it; it will then grow in much the same way, and under the same circumstances as a seed. There is no doubt that many plants could be thus multiplied as easily as the Vine, but it is equally certain that a far larger number cannot be so increased. The reason is, probably, that such eyes are not sufficiently excitable, and that consequently they decay before their vital energies are roused; and, in addition, that they do not contain within themselves a sufficient quantity of organisable matter upon which to exist until new roots are formed, and capable of feeding the nascent branch.

Mr. Knight's explanation of this, although in part applicable to cuttings only, yet seems to deserve being introduced in this place. "Every leaf-bud is well known to be capable of extending itself into a branch, and of becoming the stem of a future

EYES ARE ASSISTED BY OLD WOOD.

265

tree; but it does not contain, nor is it at all able to prepare and assimilate, the organisable matter required for its extension. and development. This must be derived from a different source, the alburnous substance of the tree, which appears the reservoir, in all this tribe of plants, in which such matter is deposited. I found a very few grains of alburnum to be sufficient to support a bud of the Vine, and to occasion the formation of minute leaves and roots; but the early growth of such plants was extremely slender and feeble, as if they had sprung from small seeds; and the buds of the same plant, wholly detached from the alburnum, were incapable of retaining life. The quantity of alburnum being increased, the growth of the buds increased in the same proportion; and when cuttings of a foot long, and composed chiefly of two-years-old wood, were employed, the first growth of the buds was nearly as strong as it would have been, if the cuttings had not been detached from the tree. The quantity of alburnum in every young and thriving tree, exclusive of the Palm tribe, is proportionate to the number of its buds; and if the number of these were, in any instance, ascertained and compared with the quantity of alburnous matter in the branches and stem and roots, it would be found that nature has always formed a reservoir sufficiently extensive to supply every bud. But those of a cutting, under the most favourable circumstances, must derive their nutriment from a more limited and precarious source; and it is therefore expedient that the gardener should, in the first instance, make the most ample provision conveniently within his power for their maintenance, and that he should subsequently attend very closely to the economical expenditure of such provision." (Horticultural Transactions, ii. 115.)

A practical mode of carrying out these views consists in detaching a mature leaf along with the bud which is to propagate.

The mode of doing this has been thus described by Mr. R. Markham, the very experienced gardener at Hewell Grange:-"The Camellia pæoniflora being the strongest growing sort with which I am acquainted, is the one I select for the purpose. In March, with a sharp knife, I cut