This group is characterized by having bristles or points on the leaf lobes and acorns which mature in two growing seasons and sprout in the spring after maturity. Red oak leaves are simple and arranged alternately on the twig. They are 7 to 11 lobed, and 5 to 9 inches long with slender petioles 1 to 2 inches long. The upper surface of the leaves are dull green while the lower surface is paler and without hairs except in the axils of the larger veins.
Twigs are stout, reddish to greenish brown and without hairs.
Winter buds are clustered at the ends of twigs, oval in shape with a sharp point, and usually chestnut brown in color. The bark on mature trees is brown to nearly black and broken up into wide, flat-topped gray ridges. On very old trees the bark may be deeply ridged and furrowed. Red oak is native to all of Iowa, except the northwest corner, although it is relatively rare in the northwest portion of its native range. It prefers soils which are moist, yet well drained and slightly acidic.