Aquatic perennial with branched stolons up to c. 1 m long usually lying just below the water surface; nodes with adventitious roots suspended in water and short-petiolate floating lvs. Basal lvs: petioles to c. 1.75 m long, very slender; lamina floating, 4.5-8.5 × 3.5-7.5 cm, suborbicular or broadly elliptic-ovate, reddish pink or reddish purple beneath, glandular-punctate beneath; margin entire; base deeply cordate with a narrow triangular sinus 2-2.5 cm deep. Fls c. 7 per cluster; pedicels to c. 7 cm long, curving upwards towards apex to carry fls above surface. Calyx 6-9 mm long; lobes lanceolate, obtuse. Corolla medium yellow, 2.5-4 cm diam.; wings of lobes c. 2-3 mm broad, with fimbriae 2-3 mm long. Style short. Stigmatic lobes broad. Capsule < 1 cm long; seeds c. 1.5 mm long, glabrous.