There are approximately 60 species in the U.S. which are generally intermediate in tolerance. Twigs are relatively stout with stellate pith and clustered buds at the end of the twig. Subgenera White Oaks Leaves are deciduous or persistent and usually have lobes without bristle tips. Fruit matures in 1 season. The inner surface of the shell is glabrous and the seed is sweet.
Wood is often with tyloses.
Range extends throughout the Northern Hemisphere. Red and Black Oaks Leaves are deciduous or persistent, usually with bristle-tipped lobes or bristles on margins and occasionally are entire. Fruit generally matures in 2 seasons. The inner surface of the shell is generally tomentose and the seed is generally bitter. Wood is often without tyloses.