CHAP. CV. CORYLA‘CE. QUE/RCUS. 1729 
roots; and if from the shoots one is selected to form the future tree, and the 
others carefully rubbed off, the tree will advance at as rapid a rate as if it 
had been sown where it was intended finally to remain; and,in cases where 
the subsoil is bad, much more so. " 
In the future culture of the oak, the trees generally require side pruning 
when 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 many 
of the American kinds are comparatively tender, they are most advantageously 
cultivated in masses. The group J‘lex forms excellent evergreen hedges, 
and most of the species belonging to it endure the sea breeze. The Nepal 
species, 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, §c. None of the oaks are so 
liable to have their branches broken by high winds as most other large 
trees; but, on the other hand, they are said to be more frequently struck by 
lightning 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 part 
of our knowledge respecting the insects which feed on the oak relates to those 
which infest the species comprising the group Robur, and those which pro- 
duce the galls of commerce and the scarlet grain, we shall defer what we 
have 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 under 
the group Robur; and others which are common to trees generally will be 
treated of in a separate chapter, in Part LV. of this work. Fortunately, though 
the insects infesting the oak often destroy, injure, or disfigure the leaves, yet 
there are but very few kinds which attack the solid wood till it is in a state 
of decay; in which respect the oak differs widely from the elm, which, as 
we have already seen (p. 1387.), is liable to have its wood destroyed by the 
Scolytus at every period of its existence. 
Study of the Species. Till the oaks of America began to attract the notice 
of botanists, the European species occasioned comparatively little difficulty. 
The American sorts, however, vary so exceedingly in their leaves at different 
seasons 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 from 
them, which shall remain constant. The descriptions of the American oaks 
which have been published are, consequently, of very little use, without 
figures; and even the figures differ exceedingly in different authors: for 
example, in the works of the younger and elder Michaux, in Abbott’s Insects 
of Georgia, in Catesby’s Carolina, and in Audubon’s Birds of America; not to 
speak of the figures inthe Nouveau Du Hamel, and other works published on 
American oaks by botanists who have not been in America, 
All the species of oaks hitherto described by botanists have been arranged 
in 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, with 
the lobes mucronate; and, 5. Leaves sinuate, but the lobes without any 
mucros. This arrangement, which has been followed by Smith, and in the 
Nouveau 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 any 
other particular than that which characterises the section. Thus, in all 
Willdenow’s sections, evergreens are indiscriminately mixed with deciduous 
kinds ; large-leaved, rapid-growing, lofty trees, with small, slow-growing, bushy 
trees; and soon. We do not mean to say that this arrangement is without 
its use; but we think it decidedly inferior to one in which the species are 
thrown into groups according to a totality of characters. Such a classification 
cannot, 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 whole 
of the species have been seen in a growing state by one botanist, it cannot 
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