Hydrocharis
Hydrocharis is a genus of aquatic plants within the family Hydrocharitaceae.
The best known species is Hydrocharis morsus-ranae, commonly called common or European frogbit, and occasionally water-poppy. The name "American frogbit" refers to another aquatic plant, Limnobium spongia.
Source: adapted by the editor from Wikipedia, the free encyclopedia; from the article "Hydrocharis". Image Credit.