Trees or shrubs. Leaves compound with many leaflets. Male catkins solitary to several; perianth united with the linear. bract, margin 3-6-lobed, irregular; stamens 3-15. Female spikes lateral, often long and many flowered, erect or recurved in fruit; bract 3-5-fid, shortly cupular, enlarged in fruit; perianth 4-fid, adnate to the ovary; ovary unilocular; styles 2-4, stigmatose; stigmas papillose-fimbriate. Nut small. Seed 2-4-lobed at the base.