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 lower 20 feet. Crown wide and irregularly shaped.
Bark
On young trees, bark is smooth and dark brown. On older trees, bark is thick and black with deep furrowed and rough broken ridges. Inner bark bright yellow and bitter because of tannic acid.
Leaf
Simple, alternate on stem, length 5 to 10 inches, lobed halfway to midrib with seven to nine triangular, bristle-pointed lobes. Crimson in spring, silvery when half grown, brown in autumn. When mature, thick dark green and shiny on upper surface and pale on lower surface. Covered more or less with down with conspicuous rusty brown hairs in forks of veins.
Fruit (seed)
Light brown nut (acorn) matures in the second season. Length is 1/2 to 1 inch. Shape is somewhat round. One-half to three-fourths of nut is enclosed in thin, dark brown, scaly cup. Kernel is yellow and extremely bitter.
Range
Found in southeastern Minnesota on dry ridges. Moderately shade intolerant, moderately fast growing.
Wood uses
Hard, heavy, strong, coarse-grained, not tough, bright reddish-brown with thin outer edge of paler sapwood. Principally used for fuel. Tannin and yellow dye made from bark.