Perennial creeping herb, rooting at the nodes, sometimes a floating aquatic. Stems often purple-red, prostrate or ascending. Leaves narrowly lanceolate, shiny dark green. Flowers solitary in the upper leaf axils, pale yellow with a darker spot at the base of the petals. Sepals and petals 5; stamens 10. Fruit a capsule, light brown with 10 conspicuous dark brown ribs.