Elodea is a genus of aquatic plants often called water weeds. Elodea
is native to North America and it is also widely used as aquarium
vegetation. The introduction of some species of Elodea into waterways
in parts of Europe, the Australia, Africa, Asia, and New Zealand has
created a significant problem, and it is now considered a noxious weed
in these areas.
Elodea canadensis, sometimes called American or Canadican waterweed or
Anacharis (a former scientific name) is widely known as the generic
water weed. The use of these names causes it to be confused with
similar-looking non-native plants like Brazilian elodea (Egeria Densa)
or hydrilla (Hydrilla verticillata). American waterweed is an
attractive aquarium plant, and is a good substitute for Brazilian
elodea since it is native to Washington's lakes, ponds and rivers.
American waterweed is usually fairly easy to distinguish from its more
notorious relatives, like Brazilian elodea and hydrilla. All of them
have leaves in whorls around the stem. However, American waterweed has
three leaves per whorl, whereas hydrilla and Brazilian elodea almost
always have more than three leaves per whorl. Brazilian elodea is also
a much larger, bushy plant with longer leaves. American waterweed also
looks very much like another native elodea, Elodea nuttallii, which
generally has three narrower leaves per whorl.
The American waterweed lives entirely underwater with the exception of
small white flowers which bloom at the surface and are attached to the
plant by delicate stalks. It produces winter buds from the stem tips
that overwinter on the lake bottom. It also often overwinters as an
evergreen plant in mild climates. In the fall, leafy stalks will
detach from the parent plant, float away, root, and start new plants.
This is the American waterweed's most important method of spreading,
with seed production playing a relatively minor role.
Silty sediments and water rich in nutrients favor the growth of
American waterweed in nutrient-rich lakes. However, the plant will
grow in a wide range of conditions, from very shallow to deep water,
and in many sediment types. It can even continue to grow unrooted, as
floating fragments. It is found throughout temperate North America,
and is one of the most common aquatic plants in Washington.
American waterweed is an important part of lake ecosystems. It
provides good habitat for many aquatic invertebrates and cover for
young fish and amphibians. Waterfowl, especially ducks, as well as
beaver and muskrat eat this plant. Also, it is of economic importance
as an attractive and easy to keep aquarium plant.
Cells of elodea...