Lesser Duckweed Lemna minor

Common Duckweek is a small, aquatic, herbaceous perennial in the arum family reaching only 3 inches high, but when grouped together, these tiny plants form a floating carpet cover on the water's surface. Flowering is rare and it is among the smallest flowering plants known. Each plant consists of a single flat leaf that floats on the surface of still waters such as ponds and lakes. The common name comes from the fact that ducks, along with other waterfowl, like to eat it.

Common Duckweed prefers full sun or partial shade and a standing water environment. It has a short lifespan, but spreads rapidly,  Its habit is to lay along the water surface with its extremities facing upwards. Duckweed can grow on wet mud and will overwinter at the bottom or ponds. As the weather warms in spring, buds will rise to the surface.

A sticky secretion from the pistol of the plants' flower attracts flies, mites, spiders, and bees.  Their contact with the substance leads to further pollination of the plant.

Although some consider its spreading nature as invasive, there are some benefits.  Waterways containing high amounts of phosphorus and nitrogen from agricultural runoff can be controlled by harvesting duckweed.  The plant helps remove these pollutants from the water.  It also discourages algae growth in water gardens and ponds.

Clemson University Home and Garden Information Center has a factsheet on aquatic weed control, including advice on controlling duckweed.

Insects, Diseases and Other Plant Problems: 

Its spreading nature can become invasive.