The branches of the post oak are so thick set, short, and crooked that this oak is seldom confused with any other. It rarely grows to be more than twenty-five or thirty feet high, and the many low, crooked branches, crowded together at the base of the trunk, give, as Emerson says, the effect of the top of a tree whose trunk is under ground. The leaves of the post oak are often held through the winter, and they are so stiff, rough, and abundant that they are, in themselves, a distinguishing mark. The specimen in the Arnold Arboretum, from which the accompanying photograph was taken, holds its leaves later in the spring than any of the other oaks. The wood is heavy, close-grained, hard, and durable, but it is difficult to season. It is used in the construction of houses, in the manufacture of carriages, and for cooperage, fencing, railway ties, and for fuel. The specific name, _minor_ (smaller), refers to the height of this oak as compared with that of the larger members of the family. The post oak is found from Southern Massachusetts—on Cape Cod, on the islands of Martha’s Vineyard and Naushon—to Northern Florida and, in certain localities, west to Eastern Kansas. [Sidenote: Black Oak _Quercus velutina_] _A large tree, 70 to 80 and (rarely) 150 feet high. Bark thick, rough, and dark. Twigs smooth, with a bitter taste. Alternate leaf-scars. Buds very downy, sharp-pointed, and large. The acorns are set in a deep, conspicuously scaly cup. The kernel is bitter._ [Illustration: BLACK OAK _Quercus velutina_ Page 92 ] 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. [Sidenote: Red Oak _Quercus rubra_]