Some of the plants in lakes and ponds are beneficial, and others are considered invasive. Birds, amphibians, reptiles and mammals make nests and feed on aquatic plants. Barrow’s goldeneye duck is just one species of waterfowl that nests in the vegetation growing in shallow water on the shores of ponds and lakes. On the other hand, plants such as purple loosestrife change entire water ecosystems with their invasive nature.
Bulrush grows in shallow water, and it is the nest of choice of different birds, reptiles, insects, amphibians and fish. Water birds also feed on the plant's seeds, and muskrats eat its stems and roots. This plant has a hard stem that tapers at the top. Close to the tapered end, short branches sprout and hold clusters of gray to brown flowers.
The cattail’s name comes from the spongy brown section of the plant's long stem, which to some resembles a cat's tail. It has creeping roots that propagate quickly in shallow water, and its stems are so hard that muskrats use them to build their homes. Groups of this plant also serve as a nesting area for red-winged and yellow-headed blackbirds, as well as others.
If you’ve ever seen a green layer of vegetation covering a large portion of a pond or lake, you were probably looking at filamentous algae, sometimes called “pond scum.” This algae, as the name suggests, is composed of millions of filaments without leaves, roots or stems that float on the surface of slow-moving water. Missouri considers it a nuisance aquatic plant because where it exists, no one can fish or swim. Filamentous algae also has the potential to block sunlight and render water intake screens useless.
The watershield is native to the state of Florida. Its oval, shield-shaped leaves float on the surface of the water, while its leaf stalks extend both above and below the water. The leaf stalks grow to depths of 6 feet and attach to the plant’s root buried in mud on the bottoms of lakes and ponds. The watershield also produces a small purple flower that stands above water on a stem.
Purple loosestrife arrived in North America from Europe in the 19th century in the luggage of immigrants who valued its purple flowers. It has since become an invasive aquatic plant, taking over any waterway where it creates roots. Other plants usually can’t compete with purple loosestrife and are eliminated from the ecosystem, which leads to the disappearance of animals dependent on them for nutrition. Purple loosestrife has a four-sided stem, close to which small purple flowers bloom on the top end. The plant's leaves appear on the stem under the flower cluster.
- Grasslands Conservation Council of British Columbia: Ponds and Lakes
- Grasslands Conservation Council of British Columbia: Ponds and Lakes: Plants
- Missouri Department of Conservation: Common Nuisance Water Plants in Missouri Ponds and Lakes
- Center for Aquatic and Invasive Plants: Watershield
- Vermont Agency of Natural Resources: Purple Loosestrife
- Pond image by Adam from Fotolia.com