Duckweed is a very small floating plant. It has shoe-sole shaped leaves with a small hair-like root hanging on its underside. It resembles a four-leaf clover and is approximately the size of a pencil eraser. It is frequently misidentified as algae. Once established, it can cover the entire water surface and resemble a golf course green. It can cut off sunlight to submersed plants and cut off oxygen to fish and other wildlife.