Annual or perennial, aquatic herb; stem hollow, spongy, trailing, reaching sometimes to a greater length, glabrous or hairy at nodes; leaves variable, often ovate-lanceolate, cordate, hastate at base, entire or sublobed, glabrous; petioles very long; flowers solitary or in few flowered, axillary cymes; peduncles 5-15cm long, 1-5 flowered; pedicels 2-5 cm; bract inconspicuous; sepals-5, free, persistent, subequal, ovate, obtuse, glabrous or nearly so; corolla purple pink, glabrous, 2-6 cm long, funnel shaped, 5 plaited; stamens-5, included; filaments unequal, filiform, woolly below, anthers oblong; disk annular, ovary 2, rarely 4 celled, ovules-4, one in each; style filiform; stigma capitate or 2-lobed; capsule ovoid, glabrous, small; seeds 2-4, broadly trigonous, glabrous or with dense, soft, minute hairs.