Monoecious trees. Leaves alternate, rarely opposite, imparipinnate, exstipu¬late, deciduous; bract solitary; bracteoles usually 2. Perianth of 3-5 tepals. Male catkins lateral, many flowered; stamens 3-40. Female flowers few to many, in terminal racemes or spikes; perianth inferior, enclosed in a cupule; carpels 2, syncarpous; ovary inferior, unilocular with 1 erect ovule; style short, with 2 stigmas. Fruit a drupe or a nut. Seed solitary, non-endospermic.