High Quality Content by WIKIPEDIA articles! "Duckweed" or "bayroot" are aquatic plants which float on or just beneath the surface of still or slow-moving fresh water bodies. They arose from within the arum or aroid family, (Araceae), and therefore, often are classified as the subfamily Lemnoideae within the Araceae. Classifications created prior to the approximate end of the twentieth century tend to classify them as a separate family, Lemnaceae.