Shrubs or trees , open-spreading, 4--8(--15) m. Bark light to dark brown, smooth. Branches ascending; twigs glabrous to sparsely pubescent, sometimes with glandular hairs. Winter buds containing inflorescences ovoid, 3--5 × 3--4 mm, acute. Leaves: petiole glabrous to moderately pubescent, with or without glandular hairs. Leaf blade nearly orbiculate to narrowly ovate or ovate-oblong, often nearly angular and slightly lobulate near apex, 4--10 × 3.5--12 cm, thin to leathery, base narrowly cordate to narrowly rounded, margins coarsely and often irregularly doubly serrate, apex obtuse to acute or acuminate; surfaces abaxially glabrous to moderately pubescent, usually pubescent on major veins and in vein axils. Inflorescences: staminate catkins lateral along branchlets on short shoots, usually in clusters of 2--3, 4--6 × 0.5--0.8 cm; peduncles 0.5--10 mm. Nuts in clusters of 2--6, completely concealed; bracts bristly, connate at summit, lengthened into extended tubular beak. Corylus cornuta was used medicinally by Native Americans as an emetic, for teething, to expel worms, to heal cuts, and as an astringent (D. E. Moerman 1986).