Succulent shrubs or trees. Stems either composed of flattened joints or terete; branches tuberculate. Areoles with up to 30 spines; glochidia present. Leaves 0 or inconspicuous, caducous. Flowers solitary. Fruit purple, red or yellow.
Derivation of name: based on Tournefort’s name for succulent plants from Opous, Boeotea, Greece.