Side veins of the leaves are unbranched and run straight to the teeth on the margins. This characteristic separates American hornbeam from the hophornbeam that has similar foliage. Teeth at the ends of the veins are larger than the teeth between the veins. Leaf margins are doubly toothed. Foliage resembles that of the black or sweet birch, but is smaller.
Buds are usually of two distinct sizes and are somewhat angled.
The smaller buds, at the terminal end, are vegetative buds. The larger, plumper buds further down the twig are mixed buds and contain both floral and leaf initials. The trunk is fluted with irregular ridges extending up and down the tree. The bark is light gray to dark bluish-gray in color and sometimes marked with dark bands extending horizontally on the trunk. The tree is commonly multi-stemmed as a result of damage from the hornbeam borer that kills the tree to the soil line, where its stump sprouts and regenerates another tree.