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Canadian Waterweed

Elodea canadensis

Please keep in mind that it is illegal to uproot a plant without the landowner's consent and care should be taken at all times not to damage wild plants. Wild plants should never be picked for pleasure and some plants are protected by law.
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Plant Profile

Flowering Months:
Hydrocharitaceae (Naiad)
Life Cycle:
Maximum Size:
3 metres long
Ditches, ponds, water, wetland.

White, 3 petals
Inconspicuous tiny whitish flowers which are seldom seen. Male and female flowers are on separate plants.
An ovoid capsule which ripens underneath the surface of the water. 6mm in diameter and filled with numerous seeds.
Densely packed whorls of oval leaves around the stems. The leaves are in whorls of 3 and 4.
Other Names:
American Duckweed, American Waterweed, Broad Waterweed, Canadian Pondweed, Common Elodea, Ditch Moss, Oxygen Weed, Pondweed, Water Thyme.
Frequency (UK):

Similar Species

Other Information


Elodea canadensis, also known as Canadian waterweed or pondweed, is a perennial aquatic plant native to most of North America. It grows submerged in fresh water ponds, lakes, and slow-moving streams. It has slender, dark green stems with whorls of three to four thin, toothed leaves. Elodea canadensis is a popular aquarium plant, and is a common nuisance species in some areas of Europe and North America. It is capable of forming dense mats that can impede water flow, reduce oxygen levels, and outcompete native species. However, it can also provide shelter and food for some aquatic animals, and can play an important role in the ecology of aquatic systems.


Canadian Waterweed (Elodea canadensis) is an aquatic plant that is commonly found in fresh water bodies across North America. It is a popular plant for aquariums, ponds and water gardens, due to its lush green foliage and ability to provide shelter and shade for aquatic animals.

This species of Elodea is a stem plant that grows in dense clusters, with leaves growing on opposite sides of the stem. The leaves are oval-shaped, with serrated edges and a glossy surface. The plant can grow up to two meters in length, and the stems can divide into multiple branches, forming a dense mat of vegetation in the water.

Despite its popularity, Canadian Waterweed can also be an invasive species, as it has the ability to quickly colonize new habitats and outcompete native plants. In some areas, it has become established in waterways and lakes, causing harm to local ecosystems by reducing the amount of light and oxygen available to other aquatic plants and animals.

To control the spread of Canadian Waterweed, it is important to limit its introduction to new water bodies and to remove any existing populations as soon as they are detected. This can be done by physically removing the plant and its roots from the water, or by using chemical treatments, such as herbicides.

Canadian Waterweed is a versatile and attractive plant that can add beauty and depth to aquariums, ponds, and water gardens. However, it is also an invasive species that can cause harm to local ecosystems, so it is important to take steps to limit its spread.

In addition to being an invasive species, Canadian Waterweed can also be a nuisance for recreational activities, such as boating and fishing. The dense mats of vegetation can clog waterways, making them difficult to navigate, and they can also interfere with fishing lines, making it difficult to catch fish.

In terms of its impact on water quality, Canadian Waterweed can contribute to eutrophication, which is the excessive growth of algae due to an increase in nutrient levels in the water. This can result in a reduction of oxygen levels in the water, causing harm to fish and other aquatic animals.

Despite these negative effects, Canadian Waterweed does have some benefits, such as providing habitat for aquatic animals, and serving as a food source for some species of fish and invertebrates. It is also a popular plant for use in laboratory experiments, as it is easy to cultivate and provides a simple system for studying photosynthesis, respiration and other processes.

To minimize the negative impacts of Canadian Waterweed, it is important to educate the public about its potential harm, and to encourage responsible practices for its use and disposal. This can include proper disposal of aquarium plants, avoiding the release of aquatic plants into natural water bodies, and using alternative species for laboratory experiments.

Canadian Waterweed is a species that has both positive and negative impacts on the environment, and it is important to be aware of its potential effects and to take steps to manage it responsibly. Whether used for aesthetic purposes or as a subject of scientific study, it is essential to take a balanced approach that considers both its benefits and its drawbacks.

It is also important to note that Canadian Waterweed is not the only invasive aquatic plant species that poses a threat to native ecosystems. Other species such as Hydrilla verticillata and European Water Chestnut are also prevalent in many areas and can cause similar impacts.

To prevent the introduction and spread of these invasive aquatic plants, it is crucial to practice proper disposal of aquatic plants and to be cautious about introducing new species into water bodies. This can include purchasing plants from reputable sources and ensuring that they are not carrying any invasive plant species or seeds.

Another way to control the spread of Canadian Waterweed and other invasive aquatic plants is through the use of biological control methods. This involves introducing natural predators, such as grass carp, to control the population of invasive species. However, these methods should be used with caution, as they can also have unintended consequences on native species.

In addition to these control measures, it is important to conduct ongoing monitoring and management of invasive aquatic plant populations. This can include regular surveys and assessments, as well as the implementation of management plans to address new invasions as they occur.

In conclusion, Canadian Waterweed is just one of many invasive aquatic plant species that pose a threat to native ecosystems. To protect our waterways and preserve the biodiversity of our aquatic environments, it is crucial to take a proactive approach to the management of these species. This includes education, responsible use and disposal practices, and ongoing monitoring and management efforts.

Distribution Map

Reproduced by kind permission of the BSBI.

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