Also known as longleaf pondweed, American pondweed is a rooted, perennial herb that has both submerged and floating leaves. It is considered a threat to 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.
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, while the less abundant, submerged leaves are smaller and blade-like. Flowers emerge from the water in densely packed, club-like spikes. Seed heads are brownish red and extend above the water on slender stalks.
This plant prefers to grow in lakes, ponds, ditches, streams and shallow water but can also grow in rapid and deep waters.
American pondweed can be found throughout the entire United States.
American pondweed is often a food source for fish, waterfowl and turtles. Because it is considered an invasive species, it is eradicated by humans with herbicide. It is also susceptible to aphid infestation.
Reproduction occurs through producing new shoots, fragmentation and seeds.