Elodea canadensis

Common Water Weed

ELODEA, CANADA WATERWEED, AMERICAN WATERWEED, ANACHARIS

Habitat: Common waterweed is found in the submersed plant community. Preferring fine, nutrient rich sediment, it grows to depths of up to several meters. This plant may be found in a wide range of environments, including freshwater ponds, slow moving streams or tidal tributaries.

Description: Common waterweed has slender stems and small, lanced shaped leaves (6-17 mm long and 1-5 mm wide). The stems, anchored bY shallow roots, grow up to one meter long, often branching profusely and forming dense, tangled stands. The leaves are attached directly to the stem (no petiole) in whorls, with three leaves per whorl. Occasionally there may be only two leaves per node, but rarely (if ever) are there more than three. The leaf edges are finely serrated, generally visible only with magnification. Small, white flowers with three petals are produced at the tips of long slender stalks and rise to (or above) the water surface at maturity. Female flowers are most often seen; male flowers are rarely produced. (Tip: Having three or less leaves per whorl helps to distinguish this plant from its invasive look alikes, hydrilla and Brazilian elodea. Both of these invaders tend to have 4 or more leaves per whorl.)

Origin and Range: Common waterweed is native to New England and much of the US.

Annual Cycle: Common waterweed overwinters under the ice as an evergreen plant, growing slowly with a reduced rate of photosynthesis. In the spring, faster growth resumes and new shoots appear. Flowering occurs early to midsummer. Reproduction is primarily vegetative through stem fragments. Seeds are rarely produced.

Value to the Aquatic Community: Common waterweed is a source of food and habitat for fish and invertebrates throughout the year. Waterfowl feed upon both the plant and upon the small organisms that inhabit the dense vegetation. Stands of waterweed may become so thick that even fish cannot penetrate the mat.

Look Alikes: Slender waterweed, Brazilian elodea, and hydrilla.