TREE, the largest of vegetable productions, rising to a considerable height, with a single stem.
Trees are divided into two principal classes, namely, fruit, and timber trees; the former includes all such as are raised chiefly, or entirely, for their edible fruit; an account of which, together with their mode of cultivation, the reader will find in alphabetical order, and also in the articles Fruit-trees, Orchard, &c.—The second division comprehends those trees, the wood of which is employed in ship-building, machinery, or for other useful purposes, such as the Oak, Larch, &c.; the culture of which has been discussed under those respective heads.—See also Timber.
The growth of trees is a subject of considerable importance; but few accurate experiments have been made, in order to ascertain their annual increase in height and bulk.—In the Philosophical Transactions of the Royal Society, for 1788, Mr. Barker states, as the result of his observations, that oak, and ash-trees, grow nearly in equal proportions, increasing about 1, or 112 inch every year. He remarks, that when the annual growth amounts to one inch in height, a coat one-sixth of an inch in thickness will accrue to the tree; and as "the timber added to the body every year, is its length multiplied into the thickness of the coat, and into the girth," more timber is produced in proportion to the increasing thickness of the stem.
The health and vegetation of trees may be greatly promoted, by scraping them; by cutting away the cankered parts; and by washing their stems, annually, in the month of February or March.—Hence, Mr. Forsyth, in his ingenious "Treatise on the Culture and Management of Fruit-trees," &c. (4to. 1l. 11s. 6d.; Longman and Rees, &c. 1802), recommends fresh cow-dung to be mixed with urine and soap-suds; and the composition to be applied to the stems and branches of fruit, forest, or timber-trees, in the same manner as the ceilings of rooms are white-washed. This operation, he observes, will not only destroy the eggs of insects, that are hatched during the spring and summer, but also prevent the growth of moss; and, if it be repeated in autumn, after the fall of the leaves, it will kill the eggs of those numerous insects, which are hatched during that season and the winter; thus contributing to nourish the tree, and to preserve its bark in a fine and healthy state.—A similar practice of washing and rubbing trees was devised, many years since, by Mr. Evelyn, and Dr. Hales, who direct it to be performed first with simple water and a scrubbing brush, and afterwards with a coarse flannel: the trees, thus managed, throve uncommonly; and Mr. Marsham relates, that a beech-tree, between spring and autumn, increased 2 five-tenths inches in thickness, which was one-tenth of an inch more than an unwashed tree.—Mr. Forsyth's mixture, however, is far preferable to common water; and, if the use of the latter fluid be attended with such beneficial effects, it may be rationally concluded, that the former will be productive of still greater advantages.
In common with other objects of the vegetable creation, trees are liable to a variety of diseases; which, if not timely attended to, eventually destroy them.—Having already treated of such affections, under the heads of Canker, Moss, &c.; we shall in this place introduce a concise account of Mr. Forsyth's improved method of curing injuries and defects in fruit, or in forest trees; for which His Majesty has graciously rewarded him; on condition that it should be published. Mr. F. directs all the decayed, hollow, loose, rotten, injured, diseased and dead parts, to be cut away, till the knife extend to the sound or solid wood, so as to leave the surface perfectly smooth. The composition (prepared in the manner described vol. i. p. 88, and rendered of the consistence of thick paint, by adding a sufficient quantity of soap-suds and urine) should then be laid on with a painter's brush, to the thickness of about 1-8th of an inch, and the edges finished off as thin as possible. Next, five parts of dry pulverized wood-ashes should be mixed with one part of bone-ashes, previously reduced to powder; and then be put into a tin-box, the top of which is perforated with holes: the powder must be sprinkled over the surface of the composition, being suffered to remain half an hour for absorbing the moisture; when an additional portion of the powder should be gently applied with the hand, till the whole plaster acquire a smooth surface.—As the edges of such excisions grow up, care ought to be taken, that the new wood may not come in contact with the decayed; for which purpose, it will be advisable to cut out the latter, in proportion as the former advances; a hollow space being left between both, in order that the newly-grown wood may have sufficient room to extend, and fill up the cavity, so that it in a manner forms a new tree. By this process, old and decayed pear-trees have, in the second summer after its application, produced fruit of the best quality, and finest flavour; nay, in the course of four or five years, they yielded such abundant crops, as young healthy trees could not have borne in 16 or 20 years. By such treatment, likewise, large, aged elm-trees, all the parts of which were broken, living only a small portion of bark left on the trunk, shot forth stems from their tops, to the height of above 30 feet, within six or seven years after the composition had been applied.—Thus it appears, that both forest and fruit-trees may be renovated, and preserved in a flourishing state; while the latter may be rendered more fruitful than at any former period.—We regret that our limits confine us to the present short account, and refer the reader to Mr. Forsyth's Treatise above cited, which is illustrated with 13 elegant engravings.