Stems prostrate, 9-35 cm, rather stout but flaccid, rooting at nodes, often submerged or floating. Leaes rather succulent, obovate to spathulate, 5-20 x 3-10 mm, glandular-punctate on upper surface, broadly rounded at apex, cuneate at base into short 3-6 mm petiole which is connected by a membrane to the petiole of the opposite leaf. Flowers 1-3 per axil; pedicels 1-1.5 mm, relatively stout especially in fruit. Calyx 2-2.5 x c. 1.5 mm in flower, c. 3 x 2.5 mm in fruit and becoming membranous with 5 strong ribs. Corolla pinkish-white, 3-3.5 mm, tube included in calyx. Capsule globose, 2.5-3 mm diam., glabrous, enclosed in enlarged membranous calyx, usually irregularly dehiscent. Seeds oblong to cuneate, dark brown, 0.5 mm, longitudinally striate.