Click on the images help you identify a black oak.
Form
Height is 35 to 75 feet, with a trunk diameter of 9 to 30 inches. Large trees have no branches on the lower 20 feet. The crown is wide and irregularly shaped.
Bark
On young trees, bark is smooth and dark brown. On older trees, bark is thick and black, with deep furrows and rough, broken ridges. Inner bark is bright yellow and bitter due to tannic acid.
Leaf
Leaves are simple and alternate on the stem, 5 to 10 inches long, lobed halfway to the midrib with seven to nine triangular, bristle-pointed lobes. Leaves are crimson in spring, silvery when half-grown, and brown in autumn. When mature, they are thick, dark green and shiny on the upper surface, and pale below. Leaves are covered more or less with down and have conspicuous rusty brown hairs in the forks of the veins.
Fruit (seed)
Fruit is a light brown nut (acorn) that matures in the second season. It is 1/2 to 1 inch long, somewhat round, and one-half to three-fourths enclosed in a thin, dark brown, scaly cup. The kernel is yellow and extremely bitter.
Range
Found in southeastern Minnesota on dry ridges. Moderately shade-intolerant and moderately fast-growing.
Wood uses
Wood is hard, heavy, strong, coarse-grained, and bright reddish-brown, with a thin outer edge of paler sapwood. Principally used for fuel. Tannin and yellow dye can be made from the bark.