In a former number, page 7l, we commenced to make some remarks on roots, a subject which has more interest, perhaps, to the planter than any other, but which is very generally neglected; carelessness marks the placing of the part on which the vitality of the tree is mainly to depend, A critic remarks, on the continually absorbing power of the roots, that the simile of a wick of a candle is certainly one of the most appropriate. The wick (as well as the spongioles of the root), by its hygrometric quality, conducts fluids to the flame, only the spongioles, being continually renewed by their constant formation onwards,.are permanent. If cut, they will bleed, and occasionally discharge sap in abundance. A case is mentioned of a very fine birch-tree, whose roots were cut through in making a new walk near it. They were about five in number, and averaged about an inch and a half in diameter, and continued bleeding so incessantly for a fortnight, that the walk, at the end of that time, stood in puddles, and the sap still babbled up through the gravel.

On examining the roots with an ordinary microscope, the discharge will be found to proceed from the whole of the exposed cells through the section, and. bubbles of air are frequently formed on the cut surface, evidently showing that some kind of gas was present, either in the sap or in the cells.

Such cases are doubtless much more common than is supposed. The sunflower, bulk for bulk, imbibes and perspires seventeen more times fresh liquor than a man, every twenty-four hours. A tree may be assumed to be a combination of hollow tubes, freely communicating with each other, and inclosed in a skin through which fluids are capable of being absorbed on the one hand, and expelled on the other. If we conceive a body of this kind, in which the tubes are nearly empty, to have its lower extremity plunged in water, the absorbing power of the skin at that part will begin to introduce the water into the interior, and this continuing to go On for a sufficient time, the tubes must necessarily become at last filled with water, rising up from below. To effect this, no attracting force at the upper end of the cylinder was necessary; every particle of water which was absorbed by the lower end having driven before it a corresponding volume of the water previously existing in the apparatus. Under the influence of this operation, the tubes would in time become full, and if unelastic, the introduction of more water would be impossible.

But if such tubes, and the skin that incloses them, were elastic and extensible, then any such quantity of water might be introduced as the apparatus could receive without bursting. If We, then, suppose that the one end of the apparatus were cut open, the sides of the tubes would collapse, and the water would be forced out till there was no more left than the tubes held in their original unstretched condition. A tree is just such an apparatus. Its tubes are nearly empty at the fall of the leaf. During winter, the roots absorb water, and fill the tubes again. By the arrival of spring, they are filled almost to bursting, and then, if the stem is cut, it bleeds; or, if the roots are cut, they bleed. Bleeding ceases as the leaves unfold. The vine, the walnut, and the bird), are all as incapable of bleeding as other trees, when their leaves are formed; because the leaves gradually empty the tubes, put an end to their distension, and prevent its recurrence as long as they remain in an active state.

The excessive loss of sap would not have taken place if the roots had been wounded or cut in the summer or autumn. In the adjoining cut (Fig. 1) is represented a tree ready for removal, with the rootlets carefully preserved from injury, which should be done whenever practicable, but in practice these rootlets are too often destroyed; and, in that case, it would have been better to cut them while the tree had its leaves on it the summer previous to the intended removal.

There is no period of the year when the roots become altogether inactive, say Professor Lindley and other authorises, except when they are actually frozen. At all other times during the winter, they are perpetually attracting food from the earth, and conveying it into the interior of the plant, where, at that season, it is stored of till it is required by the young shoots of the succeeding year. The whole tissue of a plant will therefore become distended with fluid by the' return of spring, and the degree of distension will be in proportion to the mildness and length of the preceding winter. As the new shoots of spring are vigorous or feeble in proportion to the quantity of food that may be prepared for them, it follows that the longer the period of rest from growth, the more vigorous the vegetation of a plant will become when once renewed, if that period is not excessively protracted.

Fig. 1.

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No plants which are expected to attain a large size should ever be grown in pots, but should be treated on the same principle as bur common forest-trees, with this difference, that they never should be allowed to remain more than two years, and in some cases, not so much, without being transplanted, by Which means the main roots would radiate naturally from the common centre, as in Fig. 2, and become sufficiently numerous to insure a ball of earth to adhere to them. Plants would thus be furnished of a very superior quality, and at a much cheaper rate than those mutilated and expensive deformities nurtured in pots.

In our next figure (Fig. 3) is represented a tree circumscribed by the limits of pot culture. In the former, the roots are extending in all directions near the surface in search of food; in the latter, they have a direct tendency downwards, where they neither can derive food, nor, from their position, have the same effect as the former in maintaining the perpendicular position of the tree. Camellias will be found in such and worse conditions, where care has not been taken at shifting to disentangle them, and afford them inore space for their horizontal extension.

Our next figure (Fig. 4) shows the state of a fruit or forest-tree; subjected, in early life, to pot culture; where the roots have been most confined and contorted, the supply of sap thrown into the side of the tree immediately above them has been limited and irregular, as seen by the smaller and irregular portions of the annular rings in the transverse section of the trunk; whereas, again, where the root, a, has bad the means of penetrating deeper into the soil, and, consequently, been able to collect a greater amount of sap food, the annular rings above it are larger, and more, uniform in size. Sickliness, deformity, and premature death are the results. The greatest care should be employed, in planting such a specimen, to disentangle and spread the roots carefully. The Cedar of Lebanon is frequently planted from pots, and this is one reason we see such poor specimens in this country.

Fig. 2.

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Fig. 3.

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Fig. 4.

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Where the corkscrew*, or spiral direction has been once taken by the roots, they are very apt to retain it during their lives; and if, when they have become large trees, they are exposed to a gale of wind, they readily blow out of the ground, as was continually the case with a number of rare evergreens formerly kept for sale in pots. To prevent the possibility of this occurrence, it is a good plan to place trees intended for transplantation in old baskets. Through their wicker sides the roots readily penetrate, and when this has happened, the half-decayed baskets are lifted, and "potted" in other baskets, of a larger size.

The adjoining cut (Fig. 5) is a sketch of a root of a Laricio after having been planted ten years, illustrating the effects of corkscrewing better than any description.

Fig. 5.

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