Duckweeds, or water lens, are flowering aquatic plants which float on or just beneath the surface of still or slow-moving bodies of fresh water and wetlands. Also known as "bayroot," 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 end of the 20th century classify them as a separate family, Lemnaceae.