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The black oak is distinguished by its rough, dark outer bark and rich yellow inner bark (which is seen when a small cut is made with a penknife), and its downy pointed buds. On young trees as well as old ones, the bark is very rough at the base of the trunk, and this roughness extends upwards in old trees.
The round, thin, brittle balls found on black oaks and known as oak-apples are produced by an insect which injures the leaf by puncturing it and depositing an egg. This causes irritation and an abnormal growth, from which the apple is formed. The grub which lives inside this excrescence becomes a chrysalis in the autumn, and changes to a fly in the spring, when it gnaws its way out by making a little hole through the shell.
The wood of the black oak is heavy, hard, and strong, but not tough, and it is liable to check in drying. The bark is rich in tannin, and it makes a yellow dye,—quercitron,—obtained from the inner bark. Used medicinally the bark is an astringent.
The specific name, velutina, was taken originally from the Latin word vellus, meaning shorn wool, and was applied by botanists to this tree on account of the fleecy character of the recent stems and leaves. The black oak is found growing throughout New England and in the South and West.
Red Oak Quercus rubra
A large tree, 60 to 150 feet high. The bark is fissured in long clefts, with broad, smooth places between, giving the trunk a fluted column effect. Large, sharp-pointed buds, with close scales. The red oak buds resemble to some extent those of the chestnut oak, but there is a fine hair on the scales of the red oak buds, while the scales of the chestnut oak buds are bleached and have no hair. Where the base of the bud joins the stem the buds of the red oak are more constricted than those of the chestnut oak, and the chestnut oak buds seem more sessile. Alternate leaf-scars. Acorn set in a shallow cup of fine scales.
The red oak is a lofty, wide-spreading tree of great beauty. “No other oak,” Emerson says, “flourishes so readily in every situation, no other is of so rapid growth, no other surpasses it in beauty of foliage and of trunk; no oak attains, in this climate, to more magnificent dimensions; no tree, except the white oak, gives us so noble an idea of strength.”
It is perhaps, of all the black oak group, the easiest to distinguish in winter on account of the smooth spaces between the fissures of the bark on its trunk, and its pointed buds, which are much less downy than those of the black oak.
The wood is heavy, hard, and strong, but it is not particularly valuable. It is used in the construction and interior finish of houses and for making cheap furniture.