Nymphoides crenata, commonly known as wavy marshwort, is an aquatic perennial herb of the family Menyanthaceae endemic to Australia,[4] found in all mainland states and the Northern Territory[5][6][7] It is a stoloniferous, floating, perennial with stems up to 3 m long.

The leaf lamina are ovate to circular, and deeply cordate and vary from 3 to 15 cm in length.

The flowers heterostylous, (see the gallery) and there can be from 8 to14 in clusters subtended by 1–4 stem leaves, or sometimes in spaced pairs along a short inflorescence.

[6] It grows on floodplains,[8] in swamps, lagoons, irrigation channels, and also in temporarily inundated depressions,[6] and in slow-flowing streams where the depth of the water is up to about 1.5 m deep, usually on mud, and it will persist on drying mud.

[4] Nymphoides crenata was first described as Limnanthemum crenatum in 1854 by Ferdinand von Mueller.