Spirodela polyrrhiza is a cosmopolitic floating plant, 1-3 cm, that grows quickly if there is sufficient nutrition and light. Light leaves are a sign of a shortage of micronutrients. It tends to shade light from the plants at the bottom.

Helps prevent algae by shading parts of the aquarium and using nutrients in the water. Grows larger in the wild and in optimum conditions. A decorative plant for open aquariums.