Trees evergreen. Winter buds ovoid to ellipsoid, with decussate scales. Stipules extrapetiolar. Leaves alternate, distichous, or for a few species spirally arranged. Inflorescences usually unisexual, erect, spicate, or paniculate. Male flowers in fascicles of 3-7, rarely solitary and scattered; perianth 5- or 6(-8)-lobed; stamens (8 or)9-12; rudimentary pistil very small, densely covered with curved woolly hairs. Female flowers solitary or in clusters of 3-5(-7) per cupule; staminodes when present opposite perianth lobes; ovary 3-loculed; styles (2 or)3(or 4); stigmas punctiform or shallow terminal pores.

Cupules solitary on rachis, actinomorphic or zygomorphic, rarely indehiscent, completely or partially enclosing nut; bracts sparsely to densely covering outside of cupule, spinelike or rarely scalelike or tubercles (cupule measurement always includes bracts). Nuts 1-3 per cupule, maturing after 2nd year or rarely in 1st year; abortive ovule apical. Germination hypogeal; cotyledons slightly convex, rarely cerebriform rugose.