Herbs or small shrubs, sometimes aquatic. Leaves simple or compound, opposite whorled or alternate; stipules absent. Flowers small, bisexual or unisexual. Floral tube cup-shaped, adnate to and sometimes continued above the ovary. Calyx 2–4-lobed or absent. Petals 2–4. Stamens 4–8. Ovary inferior, 1–4-locular; styles as many as the loculi, with papillose or plumose stigmas. Fruit small, indehiscent, 1–4-locular or a schizocarp separating into four 1-seeded mericarps. 8 gen., mainly southern hemisphere