Description from Flora of China
Limnanthemum coreanum H. Léveillé, Repert. Spec. Nov. Regni Veg. 8: 284. 1910.
Stems long, cylindric, rooting from nodes, unbranched. Petiole cylindric, 1-10 cm, articulated, base decurrent; leaf blade ovate-cordate to orbicular, 2-6 cm in diam., base cordate, margin entire. Flowers few to many, 4- or 5-merous. Pedicel cylindric, 1-3 cm. Calyx lobes broadly lanceolate, apex acute. Corolla white, rotate, ca. 8 mm; lobes membranous, margin laciniate. Capsules elliptic, 4-5 mm, persistent style less than 1 mm. Seeds elliptic, ca. 1 mm; seed coat smooth or with a sparsely denticulate margin. 2n = 56.
Standing water. Liaoning, Taiwan [Japan, Korea, E Russia].