Lemna minor
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Species Native to Missouri
Common Name: common duckweed
Type: Herbaceous perennial
Family: Araceae
Zone: 4 to 10
Native Range: Cosmopolitan
Height: 0.25 feet
Spread: 1 to 3 feet
Bloom Time: Rarely flowers
Bloom Color: White
Bloom Description: White (rarely flowers)
Sun: Full sun to part shade
Water: Wet
Maintenance: Medium
Flowers: Flowers not Showy
Wildlife: Attracts Birds
Uses: Rain Garden, Suitable as Annual, Water Plant, Will Naturalize

Culture

Grow on still water in full sun to full shade. Scatter small bunches of plants on the water surface after last frost date. Spreads quickly in optimum conditions. Grows best in the cool temperatures of spring and autumn. Net out excess plants as needed. Can be quite invasive in frost-free climates. As waters recede, duckweed can grow on wet mud. Plants develop buds (turions) in autumn that sink to the bottom of the body of water for overwintering. Buds rise to the surface in spring only after water temperatures warm up. In the St. Louis area it is recommended that some plants be lifted each year in fall before first frost and overwintered in a saucer of moist soil covered with 1-2” of water in a bright frost-free area or in an aquarium. If growing duckweed in ornamental pools containing fish, however, consider keeping a separate stock of plants in a fish-free pond or container for replenishing supplies in the event the appetites of the fish outpace the supply of plants.

Noteworthy Characteristics

Duckweeds are among the smallest of the flowering plants. They are deciduous, free-floating, aquatic perennials that form a rapidly-expanding mat of foliage (to 1/4” tall) on still water surfaces. Lemna minor, sometimes commonly called lesser duckweed, is perhaps the most wide-spread of the duckweeds, being found throughout the world. It is native to Missouri where it typically occurs in sloughs, ponds and slow-moving streams throughout the State (Steyermark). It is called duckweed because ducks (as well as other waterfowl) like to eat it. Fish (e.g., goldfish or carp) also consume the plants and can be an important component for population control in ornamental ponds. Duckweed is also an important food source for muskrats, beaver, birds (e.g., rails, herons) and small aquatic animals such as frogs. It is a popular addition to water gardens and ponds, where it not only provides attractive foliage cover but also discourages algae growth. Duckweed has no true leaves or stems. Each plant consists of an oval-rounded, flattened green frond (to 1/8” long) with a single downward-trailing root. Foliage is bright green. Tiny flowers are white, but rarely produced.

Problems

No serious insect or disease problems. Can be invasive.

Garden Uses

Free floating aquatic perennial for water gardens or ponds.

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