Lemnaceae

Lemnaceae, commonly known as duckweeds, are a group of very small, free-floating aquatic plants. In some taxonomic treatments they are recognized as the family Lemnaceae; in others they are treated as the subfamily Lemnoideae within Araceae. The group includes five genera: Lemna, Spirodela, Landoltia, Wolffia, and Wolffiella. They are among the smallest flowering plants, with some Wolffia species measuring under one millimeter in size.

These plants have simple, flat, leaf-like structures called fronds that float on the water surface. Many lack true stems and have only minimized rootlets that serve mainly for buoyancy and nutrient absorption. They contain a gas-filled air chamber that helps keep the fronds afloat. Reproduction is predominantly asexual, via budding of new fronds, allowing rapid population growth; under favorable conditions they can double in number within a couple of days. Sexual reproduction occurs but is relatively rare.

Duckweeds inhabit still or slow-moving freshwater environments such as ponds, lakes, ditches, and marshes. They form dense surface mats that can shade underlying aquatic life and alter light and oxygen dynamics. They are highly productive in nutrient-rich waters and play roles in nutrient cycling, wastewater treatment, and bioremediation. They are also used as animal feed and are studied for potential applications in bioreactors, biofuel research, and carbon capture. Their small size and rapid growth have made them objects of ecological and agricultural interest, as well as a useful indicator of water quality.