SafePlants

Duckweed (Lemna spp.) and Watermeal

Duckweed and watermeal are common free-floating aquatic plants often found in Pennsylvania and the UK. Duckweed, also known as water lentils, is recognized as a tiny, light-green, seed-bearing aquatic perennial.

Considerations for Pets

• Duckweed is often present in ponds or aquariums.

Considerations for Children

• Duckweed plants are delicate and easily damaged.

Scientific Name and Common Names

• Scientific Name: Lemna spp. (specifically Lemna minor, Lemna polyrrhiza, and Lemna gibba are mentioned)
• Common Names: Duckweed, Watermeal, Water Lentils, Little Duckweed, Great Duckweed, Thick Duckweed

Taxonomy and Nomenclature

• Family: Lemnaceae (Duckweed family)
• Little Duckweed (Lemna obscura): Kingdom Plantae > Division Tracheophyta > Class Magnoliopsida > Order Arales > Family Araceae > Genus Lemna
• Synonyms: Lemna obscura for Little Duckweed

Distribution and Habitat

• Commonly found in Pennsylvania and the UK.
• Duckweed is found statewide in some areas but most commonly in the piedmont, midlands, and coastal plain.
• It thrives in quiescent ponds and backwaters with little water movement.
• Open ponds or shallow wetlands with little or no shade.

Ecological Role

• Duckweed serves as food for numerous organisms in pond ecosystems.
• Can be considered a weed in some environments due to its rapid growth, covering the water's surface.

Morphological Characteristics and Growth Habits

• Free-floating aquatic plants.
• Tiny, rounded leaves (fronds) that float on the water surface.
• The fronds look like little leaves but actually are a combination of leaf and stem, attached to a rootlet that dangles down in the water
• Duckweed does not flower frequently and usually reproduces by budding.
• Duckweed is the smallest, fastest-growing, and simplest of the flowering plants.

Quirky Facts

• Duckweed is considered the smallest known flowering plant.
• Duckweed has a phenomenal growth rate and high protein content.

Interactions with Other Organisms

• Tadpoles can severely knock back String Moss, allowing duckweed to thrive due to less competition.
• Pigs can use duckweed as a protein/energy source, though with slightly less efficiency than soybean meal.
• Used as Koi food

Further Information

• Discover Life: Biology, natural history, ecology, identification, and distribution of Lemna obscura.
• Integrated Taxonomic Information System (ITIS) for species recognition.
• Endangered Resces Program for Lemna obscura (Little Duckweed) information.