Shingle oak is a medium-sized tree with a straight trunk and an open, broadly rounded crown.
Leaves are alternate, simple, 4–6 inches long, 1–2 inches wide, broadest above the middle, oblong-elliptical, with a shiny upper surface; tip with a single bristle. This is the only Missouri oak with large, entire (lobeless and toothless) leaves. Leaves turn yellowish or reddish brown in autumn; dead leaves often persist on the tree through winter.
Bark is smooth, brownish-gray when young; nearly black with broad ridges and shallow fissures with age.
Twigs are slender, dark green to reddish-brown; gray-brown, smooth at maturity.
Flowers April–May, in catkins.
Fruits September–October; acorns solitary or in pairs; nut light to dark brown, often with pale stripes, shiny, broadest at the base and rounded at the tip, about ½ inch long; cup covering a third to half the nut, with brown, flattened, hairy scales. Seed bitter; acorns ripen in autumn of the second year.
Similar species: Willow oak (Q. phellos) also has entire leaves, but they are narrower, and in Missouri it only occurs naturally in the Bootheel.