Trees or shrubs, monoecious or dioecious. Leaves in whorls, scale-like, connate, forming dentate sheaths. Inflorescences unisexual, catkin-like, the staminate ones elongate, the pistillate ones (sub)capitate. Flowers without perianth, subtended by bractlets; stamen 1; pistil 1, ovary unilocular, ovules 2, stigmas 2. Fruits one-seeded samaras, each enclosed by enlarged, more or less woody bractlets, aggregated into a cone-like infructescence.