Elodea canadensis Rich. in Michx.: Elodea, American or Canadian elodea, waterweed. Hydrocharitaceae (frog's bit family).
Native perennial. Rooted in the substrate, vegetative reproduction is by stem fragments. Stems are very slender and brittle. The leaf is stalkless; the blade is linear, 0.4 - 0.8 in (1 - 2 cm) long, narrowing to a pointed but not sharp tip, with a single main vein. There are tiny teeth on the leaf margins (may require magnification to see). Leaves are almost always in whorls of 3 (occasionally up to 7), but the lowest leaves on the stem can be alternate, opposite, or whorled. Long slender flower stalks emerge from a tubular structure, and the flower floats on the surface. Elodea differs from hydrilla and egeria in having smaller plant and leaf size, consistent whorls of 3 leaves, and a lack of spines on the lower part of the underside of the midvein. Elodea feels smoother than hydrilla. While elodea can produce dense colonies and requires control in certain areas, it does not often become a nuisance.
