Lemna minor L.
Lemna cyclostasa Elliot ex Schleid.
Lemna minima Chevall. ex Schleid.
Common duckweed is native to Asia, Africa, Europe, and North America. Lemna means “water-plant” and “minor” means “lesser”—lesser because there is a similar-appearing plant in a different genus and with larger leaves, greater duckweed.
Identification: Duckweed forms a nearly continuous mat of tiny green leaves just below the surface of freshwater ponds and slow-moving streams. The leaves are so small that colonies resemble algae or “pond scum” from a distance. Each leaf is oval, ¹/₃₂-¼" (1-8 mm) × ¹/₃₂-⅛" (0.6-5 mm), equipped with tiny air sacs for flotation. Flowers are rare and nearly invisible at about ¹/₃₂" (1 mm) in diameter. Fish and birds benefit from its relatively high fat and protein levels: “duckweed” is named for ducks’ preference for this food.
Lemna minor on Earl J.S. Rook's Flora, Fauna, Earth, and Sky ... The Natural History of the Northwoods
Lemna minor on Wayne's Word
Lemna minor on Wikipedia
Lemna minor at the Lady Bird Johnson Wildflower Center
Lemna minor on eFloras
Lemna minor description by Thomas H. Kent, last updated 12 Oct 2018.
Range: Zones 4-10: