A medium-sized tree with stout branches spreading to form an open, very wide crown. Causes a skin rash in some people.
Leaves alternate, feather-compound, to 2½ feet long, ill-scented when bruised; leaflets 11–41, 2–4 inches long, egg- or lance-shaped, pointed at the tip, margin smooth except for 2–4 glandular teeth at the base; leaf stalk swollen at the base; leaves turning yellowish-green in fall.
Bark pale grayish-brown with shallow, light-colored grooves.
Twigs stout, tan to reddish, with prominent, raised pores, ill-scented when broken, leaf scars large.
Flowers May–June, male and female flowers on separate trees, in clusters, 6–12 inches long, appearing after leaves have expanded; flowers small, about 1/3 inch wide, with 5 yellowish petals; male flowers ill-scented.
Fruits September–October, in clusters of 1–5 winged, one-seeded fruits, each fruit to 1½ inches long, wing twisted toward the end, light brown, persisting on tree into winter.