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Common Waterweed

Elodea canadensis

Common waterweed has tiny, narrow leaves along slender, branching stems. (Maryland Department of Natural Resources)
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Common waterweed has tiny, narrow leaves along slender, branching stems. (Maryland Department of Natural Resources)

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

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