Mostly bulbous herbs with acidic juice. Aerial stem reduced, creeping or rhizomatous. Leaves digitately compound, showing sleep movements. Flowers regular. Stamens monadelphous at the base; filaments 5 long and 5 short, alternating with one another. Ovary 5 locular with one or more ovules in each locule. Often heterostylous (in some European species). Fruit capsular. Seeds with an elastic testa.