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Aquatic Plants and Algae

Information on identification and management of aquatic plants from Duckweed and Watermeal to Curly Leaf Pond weed and algae including planktonic and filamentous algae. Learn how to control aquatic plants by using grass carp.

The grass carp, or white amur (Ctenopharyngodon idella) is a large member of the minnow family. Grass carp have been intentionally released into the waterways of at least 35 states as a means of biological aquatic vegetation control.

Many different species of filamentous algae exist, but all have a similar appearance and growth habit. These algae colonies begin their growth in the late winter and early spring on the bottom of the pond as warmer temperatures and sunlight activate the spores and surviving cells. Most filamentous algae growth begins in less than 3 feet of water where sunlight penetrates to the pond bottom.

Planktonic algae is algae that floats in the water column and can sometimes be confused with muddy water. It causes the water to look green, brown or reddish in color.

Coontail is a very common aquatic plant in Pennsylvania ponds and lakes. It has whorls of stiff leaves that get more compact toward the end of the stem. The leaves are forked at each end.

Nitella and Chara look like rooted, aquatic plants, but both are actually a form of algae.

Duckweed and watermeal are free-floating aquatic plants that are commonly encountered in Pennsylvania. They are commonly found in nutrient-rich ponds with stagnant or little flow.

One of more than 20 pondweed species (Potamogetons) that occur in Pennsylvania, this invasive plant from Europe frequently grows to nuisance levels in ponds.

Eurasian Water Milfoil is an invasive, nonnative, nuisance plant with long stems, often reaching to the surface of a pond, with featherlike leaves in whorls of four or five around the stem.

Elodea is one of the few pond plants that can remain green all winter long.

One of the most common native, submerged pond plants in Pennsylvania.

Proper identification of aquatic plants is essential for knowing how to manage them in your pond. This video looks at the four basic categories of aquatic plants and at some of the most common plants found in Pennsylvania ponds.