Sagittaria natans

Sagittaria natans is a species of flowering aquatic plant in the water plantain family. It has floating leaves that are linear, heart-shaped or arrow-shaped. It is native to northern Europe and Asia and often cultivated elsewhere as an aquatic ornamental in aquaria and artificial ponds. It is widespread across much of the Russian Federation and reported also from Finland, Sweden, Mongolia, Japan, Korea, Kazakhstan and China (Heilongjiang, Jilin, Liaoning, Nei Mongol, Xinjiang). It grows in slow-moving and stagnant water bodies such as ponds and small streams....read more on Wikipedia.