Herbs, perennials, epiphytes, shrubs or trees, usually succulent. Stems variously modified: cylindric, flattened or spherical, bearing complex axillary, rounded, usually raised structures (areoles) The areoles bear flowers, leaves, spine clusters and often barbed bristles. Leaves present, often deciduous, or reduced or 0. Flowers solitary, sessile (except Pereskia), bisexual, usually actinomorphic. Perianth segments in gradual transition from green sepals to often very showy petals. Stamens numerous. Ovary inferior, 1-locular. Fruit usually a berry, rarely a capsule.