Trees , to 20(-30) m. Bark light gray or gray-brown, shallowly divided into smooth or scaly plates. Twigs with distal edge of leaf scar straight or nearly so, bordered by well-defined, tan-gray, velvety ridge; pith dark brown. Terminal buds conic, flattened, 12-18 mm. Leaves 30-60 cm; petiole 3.5-12 cm. Leaflets (7-)11-17, ovate to lanceolate or oblong-lanceolate, ± symmetric, (2.5-)5-11(-17.5) × 1.5-6.5 cm, margins serrate, apex acuminate; surfaces abaxially with abundant 4-8-rayed fasciculate hairs, scales, and sometimes capitate-glandular hairs, axils of proximal veins with prominent tufts of fasciculate hairs, adaxially with scattered fasciculate hairs or becoming glabrescent; terminal leaflet present, usually large. Staminate catkins 6-14 cm; stamens 7-15 per flower; pollen sacs 0.8-1.2 mm. Fruits 3-5, ellipsoid to ovoid or cylindric, 4-8 cm, smooth, with dense capitate-glandular hairs; nuts ellipsoid to subcylindric or ovoid, 3-6 cm, surface with ca. 8 high, narrow, longitudinal main ridges, with narrow, interrupted, longitudinal ridges or lamellae between main ridges.