OAK. Oak is the name indiscriminately given to any member of the large genus Quercus, which contains about 300 species, principally distributed over the temperate regions of the Northern hemisphere. Within the tropics, in America, Oaks occur on the mountains as far South as Columbia, and, in Asia, to the Malayan Archipelago. The genus is entirely absent from Africa (except the Mediterranean region), Madagascar, Australia, the South Sea Islands, &c.; and, so far, no Oaks have been found in New Guinea. Whether looked at from the standpoint of number of species, or from the value of a large number of them from a purely commercial point of view, the genus Quercus is by far the most important one in the family Cupuliferae. As a forest-tree--at any rate, in the British Isles--the common Oak is that which undoubtedly occupies the first place. For landscape effects, too, on a large scale, the massive, rugged stems and twisted branches furnish an element of picturesqueness which is unique in character. Several of the exotic species, however, far surpass our native one in the brilliancy of the colours assumed by the decaying leaves in autumn, as well as in the rate of growth; many of the evergreen and sub-evergreen ones, too, are amongst the most beautiful of hardy trees. The British Oak (Quercus Robur) is found both in Europe and Asia, almost up to the Arctic circle. As might naturally be expected with such an extended geographical distribution, there are very many forms, some of which differ markedly from any found in this country. Of these latter, the two principal are pedunculata, with sessile leaves and long peduncles, and sessiliflora, with stalked leaves and very short peduncles. For convenience of reference, these forms are accorded specific rank under Quercus, and the principal garden forms are described under each. The great age attained by the Oak is proverbial; the age of some of the famous old trees--the Cowthorpe Oak, for example--has been estimated at 1800 years. That just mentioned is, or was, the largest Oak in England. In the "Gardeners' Chronicle," n. s., vol. xvi., p. 134, the following particulars are given respecting this tree. It may, however, be better to state that the Oak in question is growing near Wetherby, in Yorkshire, but that its ruins only now remain. The circumference at 3ft. from the ground, in 1776, was 48ft. The height of the tree as a ruin was 85ft.; in 1880, the writer of the article on "Tree Lore," from which the above data are gleaned, noticed that the old tree still had a few green leaves. The following quotation was given in a Nottingham paper, two years ago, in reply to inquiries respecting "the present condition of the trees of Sherwood Forest." The information is contained in an article by Mr. W. Senior, in Cassell's "Picturesque Europe," on "The Forest Scenery of Great Britain," in which that writer states, that at Welbeck there is the Greendale Oak, which is estimated by one authority to be 700, and by another 1500, years old. "This Oak is probably the Methusaleh of his race, although it may be noted that there are few forests which do not, through their local historians, advance plausible claims for a like distinction. The Greendale Oak, nearly 150 years ago, was deprived of its heart by the eccentric desire of a former owner to make a tunnel through the trunk. This novel piece of engineering was effected without any apparent injury to the tree; an opening was made, through which a Duke of Portland drove a carriage and six horses, and three horsemen could ride abreast. This arch is 10ft. 3in. high, and 6ft. 3in. wide. A cabinet, made from the excavated Oak wood, for the Countess of Oxford, is one of the curiosities of Welbeck Abbey (the seat of the Duke of Portland). It is ornamented with a representation of this grand old tree, which is now shored and supported against the elements, before which it must, are long, succumb. The Spread Oak of Thoresby extends its arms over 180ft. of ground, and can give shelter to 1000 horsemen. In the hollow of Major Oak, seven persons have dined with comfort; and that, of course, is impossible without unrestricted elbow-room. This tree is remarkably perfect in form, the true type of a sturdy Oak that is still prepared to brave the battle and the breeze." It would be out of place here to dilate upon the value of English Oak; but the following data respecting its durability may be of interest. In the Museum No. 1 at Kew is a block of Bog Oak, a portion of a tree found below the Roman (Hadrian's) Wall, in cutting the canal from Carlisle to the Solway Firth, in 1823. According to Bruce's "Roman Wall," a quantity of posts and rails were made of the trunks, and used for fences. There is also a portion of a pile of old London Bridge--apparently as sound as it was the day it was first worked--taken up in 1827, after having been in use about 650 years. Amongst other interesting specimens is a part of an Oak beam from the Council Chamber in the White Tower, Tower of London; this is supposed to be coeval with the building of the Tower of London by William Rufus, and the adze-marks of the woodmen or builders of that period are distinctly visible. Cork is obtained from the thick bark of Quercus Suber, a common South European Oak. Kermes is the insect which yields a scarlet dye nearly equal to cochineal, and is the "scarlet" mentioned in Scripture; it feeds on Q. coccifera, an Oak from Asia Minor, &c. The acorn cups of Q. AEgilops are largely imported from the Levant for the purposes of tanning, dyeing, and making ink. The Oak Galls of commerce are yielded by Quercus infectoria, also a native of the Levant; these are much more rich in tannin than those produced in this country. See also Quercus. Insect Pests. The number of these is legion. In Kaltenbach's "Pflanzenfeinde," there are 537 species of German insects recorded as living, more or less, on Oaks, and the number might be largely increased were the compilation continued up to the present date. Many of them, it is true, live habitually upon other trees, and on shrubs, only occasionally attacking Oaks, and seldom doing very great harm to the latter; yet even they may at times do great damage to Oaks, such as the larvae of various moths (see Hybernia, Lackey Moth, Liparis, Orgyia antiqua, &c.) to the leaves; Cockchafer grubs, Mole Crickets, &c., to the roots; Balaninus nucum, or Nut-Weevil, in the fruit, &c. It may, indeed, be said that no part of the tree is safe from the attacks of insect foes; but it is impossible here to do more than mention a few of the more interesting and important of these. Several beetles (see Tomicidae), e.g., Platypus cylindrus, Xyleborus dryographus, &c., and some moths (see Goat Moth) bore into the wood, and render it unfit for use; but, fortunately, they seldom attack healthy trees. As a precaution against them, all the dead trunks should be removed, and dead branches should be destroyed. The other moths above mentioned are hurtful by consuming the leaves of Oaks, Beech, and many other trees. But even more thorough in the extent of its ravages is a small moth (Tortrix viridana), which almost restricts itself to the common Oak. It reaches about 4/5in. in the spread of the front wings, which are green. The larvae live for a time in the buds, then in the leaves, and pupate in leaves spun together, or in the soil. In some seasons, and in certain localities, hardly a leaf is allowed to remain on the trees. Shaking the branches over sheets laid on the ground will cause the larvae of all the moths to fall on to the latter, from which they may be swept up and destroyed. The same method may be employed for the capture of various kinds of small beetles, chiefly Weevils, that gnaw the leaves and buds, as well as of Cockchafers, which, at times, do considerable damage to the trees. The leaves are frequently mined by the larvae of small moths and beetles, but the injury from this cause is too slight to call for discussion at present; and, for the same reason, the larvae that feed in the buds may be passed over in silence. Among the more frequent causes of injury to the acorns is the beetle Balaninus nucum (see Nut-Weevil). Numerous species of Green Fly attack the Oak, and, at times, must weaken the trees very greatly, covering the lower leaves with honeydew, among which grows the Fungus Capnodium quercinum (see Oak Fungi), which may, in some cases, prove hurtful to the trees. But, of all the insects that attack Oaks, probably the most striking, in respect to the effects produced by them, are the makers of the various Galls so frequent and so noticeable on Oak trees. See Oak Galls.