Usually prostrate branched annuals. Leaves alternate to sub-opposite, exstipulate. Flowers small, in axillary cymes, bracteate. Sepals 5, free, margin membranous. Petals absent or 3-5. Stamens 5-10, hypogynous. Ovary globose, bilocular, with one basal ovule in each locule. Fruit of 2 cocci. Seed reniform.