Common Name: Canadian Pondweed

General Information

Elodea canadensis is a perennial, submerged, aquatic plant growing in fresh water with erect, branched or unbranched stems that root into the substrate[, ].
The plant is harvested from the wild for local use as a medicine. It is often cultivated as an aquatic plant for ponds, cool water aquariums and slow-flowing streams[].
Elodea canadensis is considered to be a serious weed in Australia, and a principal weed in much of Europe. Impacts are mostly economic, due to a reduction in water flow, and transport disruption in severe cases, but also have significant environmental and social imapcts[]. When first introduced into European waterways in the mid nineteenth century, the plant spread rapidly to become a great pest, blocking many waterways[]. It then seemed to lose its vigour in some areas, where it is now widespread but seldom abundant[].

Known Hazards

None known

Botanical References

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Range

N. America - British Columbia to Quebec and Nova Scotia, south to California, New Mexico, Arkansas, Alabama and Florida

Habitat

Fresh water, mostly calcareous, of lakes and rivers from sea level to 2,000 metres in America[]. Slow-moving fresh water throughout most of Britain[].

Properties

Weed Potential	Yes
Medicinal Rating
Habit	Perennial
Height	1.00 m
Pollinators	Water
Self-fertile	No
Cultivation Status	Ornamental, Wild

Cultivation Details

Elodea canadensis has been known to tolerate winter temperatures down as low as -30°c[]. It has a wide climatic tolerance, being present from the cold temperate climate of Alaska to the tropics of Puerto Rico, though it may be less common as the extremes of its range. It is predominant in temperate areas of North America and Europe. Pip and Simmons (1986) in Canada, and Sheldon and Boylen (1977) in the USA, studied the maximum depths at which a number of submerged aquatic plants were found, and the maximum recorded for any species was 12 - 14 metres for Elodea. In North America it has been recorded in neutral to slightly alkaline inland waters and in fresh to slightly brackish coastal waters
A floating, submerged plant of sunny, open speces, growing well in slowly-moving water and also succeeding in ponds[]. North American plants have been recorded in neutral to slightly alkaline inland waters and in fresh to slightly brackish coastal waters[]. Plants grow more vigorously when able to root into the mud of the pond[]. Plants have been known to succeed in water as deep as 12 - 14 metres[].
A dioecious species, though occasional hermaphrodite forms are found[]. Most of the plants grown in Europe are female clones and so seed is seldom, if ever, produced[, ].
Plants perennate by means of overwintering buds that sink to the bottom of the pond in the autumn and then commence growing in the spring.

Edible Uses

None known

Medicinal

An infusion of the plant has been used as a strong emetic[].

Agroforestry Uses:

An excellent plant for growing in ponds etc, helping to oxygenate the water and, by absorbing nutrients, it helps control algae and keep waters clear[]. Colonies in the wild provide excellent cover for fish, small crustaceans, insect larvae and snails[].

Other Uses

None known

Propagation

Seed - seldom produced in Britain, if it is obtained it should not be allowed to dry out and is best sown immediately in water.
Division can be carried out at almost any time in the growing season. Simply break off a bit of plant and place in water - it will soon produce roots. The stem can be weighted with something like a stone and then thrown into a pond to allow the stems to root into the mud.