Duckweeds are the smallest of the flowering plants, which consist of tiny, green, rounded, leaflike bodies (fronds) that float on the water’s surface. Each duckweed plant (genus Lemna) is a green, leaflike circular or oval frond less than 1/4 inch across, each bearing a single short, hairlike root that dangles into the water. Giant duckweeds grow in clusters of 1-3, with 2-20 roots per frond.
They are typically found floating in thick mats of homogeneous populations in quiet streams or ponds containing high levels of organic matter. Another amazing feature of these plants is that they can double their mass in less than two days under ideal conditions of nutrient availability, sunlight and temperature. To put this into perspective, a small patch of duckweed could theoretically cover the entire surface of a 0.5-hectare pond in less than 50 days! By providing food and cover for many types of aquatic wildlife, duckweed contributes to fishing, frog and duck hunting, and more. In old, nutrient-rich ponds, and those contaminated with feedlot runoff or sewage, duckweed can spread quickly, cover the surface, and become a nuisance.