Ottelia japonicum is
an annual herb occurring in paddies, water ditches, ponds, or the
like; laying its leaves in water; blades are 10-30cm long, 2-15cm
wide, broadly lanceolate, with long petioles, margins curling in
waves. Flower stalks arise among the leaves and put
2-3cm-in-diameter white or light red-tinged flowers on the water's
surface. Flowers are bisexual; stamens 3-6 in number and styles 6,
and both are yellow. Bloom time: August to October.