Duckweed (aka Lemna Minor) has tiny, green leaves that float on the surface of the water or just below it, the plant has white flowering but the blooms are rare and inconsequential. Duckweed is one of the smallest flowering plants in the world!. Duckweed grows on still or slow-moving bodies of water and only needs water, sunlight and nutrients to grow. This plant is hardy in Zones 4-10.