Trees; trunk usually straight; bark furrowed or smooth, often gray or tan; pith mostly 5-angled in cross-section. Terminal bud terete or angled; bud scales several, unequal. Stipules small, deciduous; petiole terete or laterally compressed; leaf blade usually ovate to deltoid-ovate.

Flowering precocious; catkins pendulous. Flowers anemophilous; bracts apically lobed or laciniate, membranous, caducous; flowers with the disc obliquely cupular. Male flower: stamens 4-many; filaments short, free; anthers dull red. Female flower: ovary 1-loculed; style 1, short or not; stigmas 2-4. Capsule 2-4(or 5) valved. Seeds few to numerous, small. Cotyledons elliptic.