Annual herbs. Stipules (in ours) deeply fringed. Leaves opposite. Flowers solitary in leaf axils or in loose cymes at ends of branches, Sepals (4-)5. Petals (4-)5, deeply 2-fid, the lobes themselves sometimes lobed. Stamens 5 or fewer. Styles united below, with 3 arms. Capsule 3-valved.
Worldwide: 48 species, 46 from W USA to Patagonia, one on the Galapagos and one pantropical (D. cordata).