Spirodela polyrrhiza (Giant Duckweed)

Spirodela polyrrhiza (Giant Duckweed) is a free-floating, aquatic perennial forming a carpet of small, oval to rounded, deep glossy green leaves with a red dot on the top and dark red undersides. Each plant consists of 2 to 3 leaves, which are usually connected, up to 3-15 minute roots hanging beneath the leaves and a pouch containing male and female tiny flowers. The flowers can occur from early summer to early fall. Giant Duckweed notoriously multiplies and creates dense colonies that are an important food source for ducks, turtles, muskrats, beavers, birds and fish. It can stop the proliferation of mosquito larvae and helps remove pollutants (phosphorus and nitrogen) from the water. But, it can also become a nuisance. If it covers the surface of the water, then oxygen depletion and fish kills can occur. It will also eliminate submerged plants by blocking sunlight penetration. This plant should be controlled before it covers the entire surface of the pond. Native throughout most of the world, Giant Duckweed occurs naturally in quiet inlets of lakes, ponds, backwaters of rivers, creeks with slow-moving currents, and marshes. In temperate regions, the top part dies in the fall and the plant often overwinters as a turion. The plants then become dormant and the turions sink to the ground for overwintering. The following spring, they restart growing again and float back to the surface. Giant Duckweed is a popular addition to water gardens and ponds, where it provides attractive foliage cover and discourages algae growth. It is also an ideal system for biofuels, bioremediation, and carbon cycling due to its aspects of fast-growing, direct contact with media, and small genome size.

• Grows up to 2-3 in. tall (5-7 cm).
• Performs best in full sun to part shade on still water in water gardens, ponds or aquatic containers.
• Virtually pest and disease free.
• Reduce its spread by removing portions with a net.
• Native to North America, South America, Eurasia, and other parts of the world.