How to ID and Treat Aquatic Weeds

Wondering what type of weed is in your pond? It could be many different things.

For the health of your pond, it’s important to understand which types you have and how to manage them.

These are just a few that you may see in your pond:

Duckweed

Common duckweed is found throughout Mississippi, but several species are present in the state. This weed draws nutrients directly from the water and can quickly take over. 

Common duckweed has one to three leaf-like petals in its body, called a thallus. Thalli petals are pale green, flat, and round to oval. They are about 1/16 to 1/8 inch long. Each plant has a single root that may hang an inch or more below the leaf. Several to many plants may cluster together, forming a floating mat on the water surface.

Although some ducks eat duckweed and are responsible for moving them from pond to pond, it is not recommended for any management purpose. 

Find more information and management recommendations for duckweed in MSU Extension Publication 3735-42.

Water Hyacinth 

The floating growth form of this non-native, highly invasive species can quickly cover a pond with a 3-foot-high thick, heavy mat. It also grows in a rooted form.

This species is easily identified by its leathery, spongy, spoon-like leaves that feature parallel striations (wrinkles or ridges) along their length. Stems are spongy and buoyant, and smaller plants often have enlarged bulbous areas on stems that provide buoyancy. 

Young colonies can be misidentified as frog’s-bit; however, major veins will be evident in frog’s-bit leaves and will be absent in water hyacinth leaves.

The roots are purple to black and feathery. During the summer, the plant produces very showy, light-purple flowers with darker purple and yellow highlights.

Find more information and management recommendations for water hyacinth in MSU Extension Publication 3735-45.

Cattail

Two species—common and Southern cattail—are found in Mississippi. Standing between 5 and 8 feet tall, they have stout stems and broad, linear leaf blades. They also have the characteristic cigar-like flowering spike, which is dense and brown before erupting into a white, downy mass in the fall.

Cattail is used aesthetically by some and provides habitat and food for wildlife. But these plants grow into dense stands along the shoreline, interfering with shoreline access in recreational ponds. If you use them for these purposes, keep in mind that you’ll need to frequently take steps to keep them from spreading aggressively.

Throughout history, cattails have been used for medicinal purposes, and many parts of the plant are edible.

Find more information and management recommendations for cattail in MSU Extension Publication 3735-21.

You can find many more publications on aquatic weeds by searching for the keyword “ponds” on the MSU Extension publications web page.