Succulent herbs with CAM photosynthesis and simple opposite succulent leaves with pinnate venation, epidermis with many large, bladderlike cells. Flowers are solitary or cymose, with uniserate perianth, a hypanthium, and many stamens. Ovary is inferior or superior, usually with axile placentation and the presence of betalains. Fruit usually a loculicidal, septicidal or circumcissile capsule.