Description from Flora of China
Trees to 30 m tall; crown broadly ovoid. Branchlets olive green when young, becoming orange to grayish yellow, terete, sometimes angled, glabrous. Buds purplish brown or yellowish brown, long conical, glabrous, viscid. Leaves of short branchlets with petiole terete, 2-7 cm, glabrous; leaf blade ovate, elliptic-ovate, elliptic, or narrowly ovate, sometimes broadly or orbicular-ovate, (4.5-)5-10 × 3.5-7(-8.5) cm, broadest below middle, abaxially greenish white, adaxially bright green, glabrous, base rounded, rarely subcordate or broadly cuneate, apex acuminate or mucronate; lateral veins 5-7 on each side, raised. Leaves on long shoots larger, ovate-oblong, 10-20 cm, base usually slightly cordate. Male catkin 5-6 cm. Male flower: stamens 30-35. Female catkin 4-5 cm, 10-15(-20) cm in fruit. Female flower: stigma 2-4-lobed. Capsule ovoid, 6-9 mm, (2 or)3- or 4-valved. Fl. Mar-May, fr. May-Jul. 2n = 38*, 40*.
* Valleys, along rivers; 800-3000 m. S Gansu, Hebei, Liaoning, Nei Mongol, E Qinghai, Shaanxi, Shanxi, Sichuan, Yunnan, Zhejiang.