Species in the genus Diodia:

Diodia teres / Oofutabamugura
Diodia virginiana / Merikenmugura

Diodia virginiana / Merikenmugura メリケンムグラ

Diodia virginiana, a native of North America, inhabits moist/damp sections of riverbanks or ridges between paddies. Stems branch out on all sides at the bases, making mats and leaves opposite, broadly linear, with leaf surfaces deep green and somewhat leathery. Flowers are white, emerging from leaf axils, and cylindrical, with four lobes at the tips. Blooming time: June-August.