Description from Flora of China
Shrubs, perennial herbs, or rarely annuals. Leaves opposite, even-pinnate or rarely simple; petiole herbaceous or membranous; leaflet blades plane or sticklike, fleshy. Flowers axillary, solitary or paired. Sepals 4 or 5, sometimes caducous. Petals as many as sepals, orangish red, white, or yellow, sometimes with an orange claw or pale along margin, rarely apetalous. Stamens 8-10, abaxially with scale-form appendages. Ovary 3-5-locular. Capsule winged or not, dehiscent or indehiscent, with 1 to several seeds per carpel.
More than 100 species: arid and semiarid regions of N Africa, C, N, and W Asia, Australia, S Europe; 19 species (two endemic) in China.