Deciduous trees. Buds with several unequal scales. Leaves alternate; petiole usually long, terete or flattened, lamina entire or lobed, linear to rhombic ovate, dentate, serrate; often dimorphic on long and short shoots. Flowers appearing before leaves, anemophilous, in elongate, cylindrical, pendent, pedunculate catkin. Each flower in the axil of a laciniate or toothed bract; pedicellate; disc cup-shaped. Stamens 4-many, filaments free. Ovary sessile, unilocular, surrounded at the base or up to three quarters of its length by the disc; ovules many on 2-4 parietal placentas, style short, stigmas 2-4. Capsule 2-4 valved; seeds minute, numerous, with a long dense tuft of silky hairs.