A large tree with a straight trunk and rounded, open crown. The nuts, spicy odor, large feather-compound leaves, and chambered pith in the twigs help identify it.
Leaves alternate, compound, 1–2 feet long, with 11–23 leaflets. Leaflets 3–5 inches long, 1–2 inches wide, broadest below the middle, the end leaflet smaller than side ones or absent; margin toothed; upper surface yellow-green; lower surface paler, hairy.
Bark grayish-brown or black, grooves deep, ridges broad with sharp or rounded edges, roughly forming diamond-shaped patterns, chocolate-colored when cut.
Twigs stout, rigid, brown to gray-brown, hairy; end bud about ½ inch long; pith light brown, chambered when cut lengthwise.
Flowers April–May. Male flowers in catkins, female flowers in a short spike on the same tree.
Fruits September–October, usually single or in pairs. A green rounded husk, 1½-2½ inches across, covers the round, hard, bony, dark brown or black nut. The kernel is oily, sweet, and edible.