Lemna aequinoctialis

Lemna aequinoctialis, the lesser duckweed, is a tiny, floating aquatic plant in the aroid family, found in quiet, still waters of the Southern U.S., as well as Mexico and some Caribbean Islands. Additionally, it can be found from the state of Virginia south through Florida, north to Nebraska and even into southern Wisconsin. It is also widespread in the American Southwest (and most of Mexico, including desert), from Texas to the coast of California, preferring lagoons and still ponds, which it accesses via seasonal flooding and occasional precipitation. Fronds are generally triple-nerved, green, and measure up-to 6 mm long. Flowers are single-ovulate, with a small utricular scale open on one side. Seeds have 8–26 ribs. Due to its fast growth and hardy nature as a floating plant, lesser duckweed has become quite prevalent in the aquarium hobby, where it is maligned by some aquarists, while valued by others for absorbing excess nutrients in the water and shading fish from overhead light......read more on Wikipedia.