Stem: None.

Flower: Tiny, rarely seen. Arises from a pouch in the thallus.

Fruit: Inconspicuous, usually 1 seeded.

Root: Lesser: Single short rootlet hangs from the underside of each plant. Star: Often rootless.

Propagation: New plants bud from pockets on either side of the parent plant and eventually break apart. Overwinters as winterbuds on the lake bottom, but rarely reproduces from seeds. Distributed by wind and on the bodies of birds, and aquatic animals. A single lesser duckweed plant can reproduce itself about every 3 days under ideal conditions in nutrient-rich waters.

Importance of plant: Food for fish and waterfowl and habitat for aquatic invertebrates. Because of its high nutritive value, duckweeds have been used for cattle and pig feed in Africa, India, and southeast Asia. Sometimes used to remove nutrients from sewage effluent.

Distribution: Throughout much of the temperate and subtropical regions of the world.

Habitat: Still and slow moving waters in many freshwater habitats. Often found along the shoreline after water levels have dropped.

May be confused with: Giant-duckweed (Spirodela polyrrhiza) which has a cluster of 6 to 18 roots from each thallus and is green on top and brown on the bottom, watermeal (Wolffia) which is smaller and rootless, mud midget (Wolffiella gladiata), which is much longer than broad and lacks rootlets, and Mexican water fern (Azolla mexicana), which is greenish red with a fuzzy, nubby texture. Another duckweed species (Lemna turionifera) also occurs in Washington, but is very difficult to differentiate from lesser duckweed. Lemna turionifera is reddish on the under surface, produces overwintering turions, and has a slightly different vein pattern. 

Photographs: Closeup of Lemna minor, massed along shoreline, 
Lemna trisulca closeup

Line Drawings: Lemna minor