Duckweed is a floating freshwater plant and is one of the world’s smallest flowering plants. Individual lesser duckweed plants are tiny, round, bright green disks, each with a single root that floats in the water. They are found massed together in floating mats. The leaf-like body, or tallus, is 2 to 5 millimetres in diameter. The tiny flowers emerge from a pouch in the tallus.
The plants are widespread throughout temperate regions of the Northern and Southern Hemispheres, floating freely in freshwater ponds, marshes, lakes and quiet streams. The plants spread rapidly across quiet bodies of water that are rich in nutrients and grow best in water with high levels of nitrogen and phosphate.