1726

ARBORETUM AND FRUTICETUM.

PART Ili.

The bark of Q. S'uber furnishes suberine, the suberic acid, and a productby far more important than that of any species of the genus, cork ; a substancewhich is not produced by any other tree whatever, in sufficient quantities tobe applied to any useful purpose.

The leaves, the dowers, and the fruit, according to Bose, afford nourish-ment to more than 200 species of insects, even in the neighbourhood of Paris;and some of these insects are either valuable themselves in the arts, or theyare the cause of excrescences, such as oak galls, which are valuable. Theleaves of Q. coccifera afford nourishment to the Coccus ilicis, a hemipterousinsect, which is used in medicine under the name of kermes, and has beenemployed in dyeing scarlet, from the remotest antiquity, under the name ofscarlet grain. This insect is produced, and cultivated for commerce, in thesouth of France, and in various parts of the south of Europe, and of the East.Oak galls, which are much in demand for the manufacture of ink and for dyeingblack, are produced on most of the deciduous European species, and are veryabundant on the section Robur ; but the galls of commerce are chiefly pro-duced by the Q. infectoria, a native of Asia Minor and the adjoining countries.All the smaller parts of oaks, such as the spray, buds, leaves, flowers, andfruit, may be employed in tanning; and, accordingly, the cups, or calyxes, ofsome species are in use for this purpose, more particularly those of the valoniaoak (Q. AE'gilops), a native of the Archipelago. The leaves of the section.Robur are used as a substitute for spent tanner’s bark in hot-houses; andbeing slow in decomposition, are found to retain the heat for a longer periodthan those of any other European trees.

The acorns of all the species are edible ; and, in every country where theoak abounds, they form the most important part of the food of wild quadru-peds of the fructivorous or omnivorous kinds, and of some birds. The wildanimals most useful to man, which are nourished by them, both in Europeand America, are the wild boar, the stag, and the goat. In Asia, pheasantsand pigeons, with other birds in a wild state, eat acorns, no less than wild qua-drupeds. In North America, cows, horses, swdne, bears, squirrels, pigeons,and wild turkeys devour them. Among the domestic animals which eat andthrive on acorns, the principal is the swine; but there are few animals andbirds, in a state of domestication, Bose observes, that may not be made tolive and thrive on them, however unwilling they may be to touch them atfirst. In the earlier ages, there can be no doubt that acorns, in the countrieswhere they were produced, were the food of man ; and they' are still, as wehave seen, eaten in some parts of the south of Europe, the north of Africa,and the west of Asia. The kinds which produce the acorns most valuedfor eating are, Q. I' lex, Q. Ballota , Q. gramUntia, and <2. R'sculus. The degreeof bitterness in acorns, produced by the same species, varies exceedingly ondifferent trees ; and were any kind of oak to be introduced into orchards as afruit tree, it would be advisable to select only the best varieties of particularspecies, and propagate these by grafting. There are even varieties of Q.Robur which produce acorns much less bitter than others; and we havereceived some from a tree of this species, in the south of France, which ac-cording to Dralet, are so sweet as to be eaten by the inhabitants. (See lle-cherches sur les Chines a Glmids dou.v, p. 178._)

The entire tree or shrub, in the case of every species of oak, may be con-sidered as highly ornamental: the least so are the willow-leaved oaks, andthe most so the lobed and deeply sinuated leaved kinds. The foliage, even,of the same species, and more especially of the deciduous kinds, varies ex-ceedingly ; not only on different individuals, but on the same individual atdifferent seasons of the year. In spring, the leaves of many of the decidu-ous kinds are small, delicate, and beautifully tinged with yellow and red; insummer, they are broad and green; and in autumn, coriaceous, and of arusset brown, scarlet, or blood-red colour. Nothing can be more remarkablethan the variation in the forms of the leaves, in the same individual, in someof the American species; those of the tree, when young, being sometimes