American Pondweed
Potamogeton nodosus

Also known as longleaf pondweed, American pondweed is considered a nuiance species. It is a rooted, perennial herb that has both submerged and floating leaves.

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A thick mat of American pondweed grows along the edge of a river.
American pondweed grows in lakes, ponds, ditches, streams and shallow water/ (Photo courtesy of Cassi Saari/iNaturalist CC BY-NC, cropped)

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Appearance

The leaves of American pondweed are attached to a stem that can grow up to 6 feet long. Floating, oval-shaped leaves are 4 to 7 inches long and 1 to 2 inches wide. Submerged leaves are smaller, blade-like and less abundant. Flowers emerge from the water in densely packed, club-like spikes. Seed heads are brownish red and extend above the water on slender stalks.

Predators

Because it is considered a nuisance species, American pondweed is eradicated by humans with herbicide. It is also susceptible to aphid infestation.

Reproduction and life cycle

Reproduction occurs through producing new shoots, fragmentation and seeds.

Did you know?

  • Although native to the Bay region, American pondweed is considered a threat to other native submerged aquatic vegetation because of its tendency to form dense mats that block the sunlight these plants need to grow. However, these dense mats are considered a good source of shelter and food for fish, diving ducks and invertebrates.
  • American pondweed is often a food source for fish, waterfowl and turtles.

Sources and additional information

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