Herbs (mostly, in ours), shrubs, climbers or rarely trees. Stems usually with sheathing stipules (ochreae). Leaves simple, alternate (rarely subopposite). Flowers actinomorphic, bisexual or unisexual. Petals 0. Perianth segments 3-6, sepaloid or petaloid, free or connate, persistent. Ovary superior, 1-locular, with a solitary ovule. Fruit a nut, indehiscent, hard, 3-angled or biconvex, usually enveloped in the perianth. Seeds with abundant endosperm.