Terrestrial or semi-aquatic annual herbs; stems prostrate. Leaves simple, sessile, semi-succulent, not gland-dotted. Flowers solitary, axillary at medial or distal nodes; bracteoles absent. Calyx-tube 5-angled, shortly 5-toothed; corolla actinomorphic, equally 5-lobed, tube symmetrical at base, neither swollen nor spurred; stamens 4 or 2, filaments not spurred, anthers of each pair joined, with 2 confluent but divergent locules; stigma with 2 lamellate or filiform (not in Victoria) lobes, receptive on inner surface and irritable, closing together when touched. Capsule loculicidal, included in enlarged calyx; septa united to the 2 valves and to the central column; seeds many, reticulate.
