Leaves 9′—15′ long, with slender dark red puberulous or tomentose petioles, and 7—13 ovate-lanceolate long-pointed falcate leaflets symmetrical and rounded or cuneate and unsymmetrical and oblique at base, finely or coarsely serrate, sessile or stalked, 3′—5′ long, ½′—1½′ wide, covered with yellow glandular dots, thin, dark green above, brown and lustrous or tomentose on the lower surface, especially on the slender midrib and primary veins, the terminal leaflet more or less decurrent by its wedge-shaped base on a slender stalk or rarely nearly sessile. Flowers: staminate in solitary or fascicled hirsute aments 2½′—3′ long, covered like their bract with yellow glandular pubescence; stamens 6, with yellow puberulous anthers; pistillate in several flowered spikes, oblong, slightly flattened, 4-angled, glandular-pubescent. Fruit often in 3 or 4-fruited clusters, much compressed, usually broadest above the middle, rounded at the slightly narrowed base, rounded or abruptly narrowed at apex, conspicuously 4-winged, dark brown or nearly black, covered more or less thickly with bright yellow-scales, 1½′ long, 1′—1¼′ wide, with a thin brittle husk splitting tardily and usually only to the middle; nut flattened, slightly obovoid, nearly as broad as long, rounded and abruptly short-pointed at apex, rounded at the narrow base, 4-angled and ridged, dark reddish brown, and longitudinally and very irregularly wrinkled, with a thin shell; seed oblong, compressed, dark brown, irregularly and usually longitudinally furrowed, very bitter. A tree, occasionally 80°—100° high, with a trunk rarely exceeding 2° in diameter, slender upright branches forming a narrow head, and slender dark reddish brown or ashy gray lustrous branchlets marked by numerous pale lenticels, at first slightly glandular and coated with loose pale tomentum, glabrous or puberulous during the summer, and marked during the winter by small nearly oval or obscurely 3-lobed slightly elevated leaf-scars, growing dark red-brown and ultimately gray. Winter-buds slightly flattened, acute, dark reddish brown, covered with caducous yellow scales; terminal ⅛′—¼′ long, often villose; axillary much smaller, frequently nearly sessile, often solitary. Bark ½′—⅔′ thick, separating freely into long loose plate-like light brown scales tinged with red. Wood heavy, strong, close-grained, rather brittle, dark brown, with thick light-colored or often nearly white sapwood; occasionally used for fencing and fuel.