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Common Waterweed

Elodea canadensis

Common waterweed is a bay grass with tiny, narrow leaves along slender, branching stems. It grows in slow-moving fresh waters throughout the Chesapeake Bay watershed.

Appearance:

• Slender, branching stems
• Tiny, narrow leaves that are straight or oval-shaped and grow in whorls of three along each stem
• Whorls become more crowded toward the tip of the stems
• Leaves have extremely tiny teeth that may only be visible under magnification
• From July-September, tiny flowers grow on long stalks from a tubular structure at the leaf axil
• Weak, thread-like root system

Habitat:

• Grows mostly in slow-moving fresh waters, but occasionally found in brackish waters
• Often found in areas rich in nutrients and calcium

Range:

• Found in the upper Chesapeake Bay and freshwater streams and rivers throughout the Bay watershed

Predators:

• Migratory waterfowl, especially ducks
• Muskrats and beavers

Reproduction and Life Cycle:

• Usually reproduces asexually when stem fragments bud and grow into new plants
• Rarely reproduces sexually because male plants are very uncommon. When sexual reproduction occurs, the plants produce cylindrical capsules that contain several seeds.

Other Facts:

• Also known as Canadian waterweed
• Provides good habitat for fish, amphibians and aquatic invertebrates
• Can be confused with hydrilla. You can distinguish common waterweed by its leaves, which grow in whorls of three and do not have visible teeth.

Sources and Additional Information:

• Underwater Grasses in Chesapeake Bay & Mid-Atlantic Coastal Waters by Peter W. Bergstrom, Robert F. Murphy, Michael D. Naylor, Ryan C. Davis and Justin T. Reel
• Life in the Chesapeake Bay by Alice Jane Lippson and Robert L. Lippson
• Chesapeake Bay: Nature of the Estuary, A Field Guide by Christopher P. White
• Bay Grass Key: Common Waterweed – Maryland Department of Natural Resources
• PLANTS Database: Elodea canadensis – USDA Natural Resources Conservation Service

Places:

• Susquehanna River Water Trail – Lower Section – Harrisburg, Pennsylvania to Havre de Grace, Maryland
• Potomac River Water Trail – Washington, D.C. to Point Lookout, Maryland
• Mathews Blueways Water Trails – Mathews County, Virginia