Duckweed is the name of several species of tiny plants that float on pools and ponds. A duckweed has no ordinary stem or true leaves. It consists of a flat green structure, usually with a single hairlike root underneath. The common duckweed is the smallest flowering plant known. It measures only 1/16 to 3/16 inch (1.6 to 4.8 millimeters) long. Duckweeds are sometimes grown as food for ducks and fish.
