365 Urban Species. #195: Duckweed
Photos by cottonmanifesto. Location: Ward's Pond, Boston.
Urban species #195: Duckweed Lemna minor
The reaction that most people have when they see duckweed is "what's wrong with that pond?" This miniscule floating plant reproduces vegetatively frequently spreading to cover the entire surface of small bodies of water. Duckweed doesn't necessarily indicate that a pond is polluted, but it does do well in water rich in nutrients, and fertilizer or sewage runoff can create that condition. Duckweed also tolerates a wide range of water pH, including the acid conditions typical of urban environments. The plant can have a beneficial effect on ponds, absorbing ammonia and reducing murk suspended in the water. Currently researchers are studying duckweed's usefulness as a bioremediation agent, to remove certain toxic chemicals from water. Ducks feed on duckweed and transport it from one body of water to another, as the small plant clings to their feathers and feet. Carp and goldfish eat it as well.
This duckweed in Franklin Park fully covers the surface of the pond, except for where the ducks swam through it.
