Azolla

Azolla - A. Caroliniana is a very small and curious water-plant, which floats on water quite free of soil, the tufts of delicate green leaves like tiny emeralds. During summer it will grow out of doors, and then becomes bronzed, and perhaps it is prettier when light green, as it is in the greenhouses or window. Syn. A. rubra. A. pinnata is a distinct species.