Trees or shrubs. Male flowers in solitary or axillary clusters of 2-4-catkins; bracteoles 2, not united to the bract. Stamens 2, filament forked and separating the anthers. In female flowers the 2 bracteoles are united to the bract to form a 3-lobed fruiting scale which is deciduous. Nut with a mem¬branous or winged margin.