CHAP. CV.

coryla'cete. que'rcus.

1729

roots; and if from the shoots one is selected to form the future tree, and theothers carefully rubbed off; the tree will advance at as rapid a rate as if ithad been sown where it was intended finally to remain; and, in cases wherethe subsoil is bad, much more so.

In the future culture of the oak, the trees generally require side pruningwhen the object is a straight clean trunk. As most of the species grow erect,the hardier deciduous kinds are well adapted for hedgerows; but, as manyof the American kinds are comparatively tender, they are most advantageouslycultivated in masses. The group L'lex forms excellent evergreen hedges,and most of the species belonging to it endure the sea breeze. The Nepalspecies, as far as they have hitherto been introduced, require, even in the cli-mate of London, the protection of a wall.

Accidents, Diseases, Insects, parasitic Plants, fyc. None of the oaks are soliable to have their branches broken by high winds as most other largetrees; but, on the other hand, they are said to be more frequently struck bylightning than other broad-leaved trees of the same size, or than needle-leaved trees of any height. The oak is subject to few diseases, notwithstand-ing the many kinds of insects that live upon its leaves. As the greater partof our knowledge respecting the insects which feed on the oak relates to thosewhich infest the species comprising the group /iobur, and those which pro-duce the galls of commerce and the scarlet grain, we shall defer what wehave to say on this subject till we come to treat of the species alluded to.The fungi and lichens which live on the oak will be found noticed underthe group i26bur; and others which are common to trees generally will betreated of in a separate chapter, in Part TV. of this work. Fortunately, thoughthe insects infesting the oak often destroy, injure, or disfigure the leaves, yetthere are but very few kinds which attack the solid wood till it is in a stateof decay; in which respect the oak differs widely from the elm, which, aswe have already seen (p. 1387.), is liable to have its wood destroyed by theAcolytus at every period of its existence.

Study of the Species. Till the oaks of America began to attract the noticeof botanists, the European species occasioned comparatively little difficulty.The American sorts, however, vary so exceedingly in their leaves at differentseasons of the year, in different stages of their growth, and in different lo-calities, that it is next to impossible to fix on a specific character, taken fromthem, which shall remain constant. The descriptions of the American oakswhich have been published are, consequently, of very little use, withoutfigures; and even the figures differ exceedingly in different authors: forexample, in the works of the younger and elder Michaux, in Abbott’s Insectsof Georgia, in Catesby’s Carolina, and in Audubon’s Birds of America; not tospeak of the figures in the Nouveau Du Hamel, and other works published onAmerican oaks by botanists who have not been in America.

All the species of oaks hitherto described by botanists have been arrangedin sections founded on a single character taken from the leaves. Willdenow,for example, has arranged them in the five following sections : such as, 1.Leaves entire ; 2. Leaves toothed ; 3. Leaves lobed ; 4. Leaves sinuate, withthe lobes mucronate ; and, 5. Leaves sinuate, but the lobes without anymucros. This arrangement, which has been followed by Smith, and in theNouveau Du Hamel and other works, has, like all others of the kind, the dis-advantage of bringing together species which are not allied in perhaps anyother particular than that which characterises the section. Thus, in allWilldenow’s sections, evergreens are indiscriminately mixed with deciduouskinds ; large-leaved, rapid-growing, lofty trees, with small, slow-growing, bushytrees; and so on. We do not mean to say that this arrangement is withoutits use; but we think it decidedly inferior to one in which the species arethrown into groups according to a totality of characters. Such a classificationcannot, in the case of this genus, in our opinion at least, be effected satisfac-torily either from dried specimens or drawings ; and, therefore, till the wholeof the species have been seen in a growing state by one botanist, it cannot

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