Duckweed
Lemna species


For ponds without fish the only species that is normally recommended is Ivy-leaf duckweed, Lemna trisulca, because it is the smallest leafed and least invasive.


Duckweed has a broad range of hardiness, growing well in zones
2 - 11.

There are several different species of this generia available, but one - Lemina minor - can be found in stagnant ponds everywhere, usually as a bright green mats of tiny leaves covering the surface.  Lemina minor normally consists of two tiny leaves with a thin white root hanging below each, close to their junction.

Duckweed is a fast grower and is used to shade the water's surface, helping control algae and water temperature.  Many people have problems controlling duckweed in their water gardens. If you have Japanese Koi in the pond the problem reverses and if the fish are numerous or large, you can't seem to keep any in the pool at all. Koi love eating it, and in many cases eat the duckweed faster than you can supply it. Many people have to grow it in separate washtubs or containers, because the fish will completely clean it out of the pond.