Fraxinus pennsylvanica is a medium-sized deciduous tree reaching 12–25 m (39–82 ft) (rarely to 45 m or 148 ft) tall with a trunk up to 60 cm (24 in) in diameter. The bark is smooth and gray on young trees, becoming thick and fissured with age. The winter buds are reddish-brown, with a velvety texture. The leaves are 15–30 cm (6–12 in) long, pinnately compound with seven to nine (occasionally five or eleven) leaflets, these 5–15 cm (2–6 in) (rarely 18 cm or 7 in) long and 1.2–9 cm (1⁄2–39⁄16 in) broad, with serrated margins and short but distinct, downy petiolules a few millimeters long.