Duckweed has tiny, usually three-lobed leaves with rootless that hang down in the water. Watermeal appears as minute green grains floating on the water. Dense populations of these weeds often form a green blanket on the water surface. This group of weeds includes those growing along the margin of the pond as well as in other shallow waters. Their stems and leaves protrude above the water surface.
Examples are cattails, bulrushes, arrowhead and spatterdock.
Some, especially cattails, may spread rapidly by growth of underwater stems and may reach depths of three feet or more. Some are loosely rooted and others are firmly rooted. Still others appear to be suspended fragments or clusters. Some have a few leaves that float on the surface, while many blossom and produce seed on a stem that extends above the water surface. This general group is referred to as submerged weeds.