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American Pondweed

Potamogeton epihydrus

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:
Potamogetonaceae (Pondweed)
Life Cycle:
Maximum Size:
2 metres long
Ditches, gardens, ponds, water.

Green, 4 petals
Green flower spike. Usually up to 5cm in length but sometimes up to 15cm.
A dry, single seed (achene).
The floating leaves are narrow, oval and with flattened stems (up to 8cm long and 3cm wide). The submersed leaves are stalkless, linear and much longer. Profound, parallel leaf veins. Found along Rochdale Canal, near Halifax. Grows in shallow, still water.
Other Names:
Floating-leaved Pondweed, Nuttall's Pondweed, Ribbonleaf Pondweed.
Frequency (UK):
Rarely seen  

Other Information


Potamogeton epihydrus, also known as floating-leaved Pondweed, is a perennial aquatic plant that is native to North America. It is commonly found in freshwater ponds, lakes, rivers, and streams. The leaves of the plant are glossy and floating on the water's surface, they are oblong to lanceolate in shape and have a smooth edge. The stems are long and thin and are anchored to the bottom by rhizomes. The flowers are small and inconspicuous, and arranged in spikes at the top of the stem. They typically bloom in late spring to early summer. It is an important food source for waterfowl and aquatic animals, and it also provides cover and habitat for fish and other aquatic organisms. It's considered a good oxygenator for the aquatic ecosystem and it's also used as an ornamental plant in water gardens and ponds.


American pondweed, scientifically known as Potamogeton epihydrus, is a submerged aquatic plant that is native to North America. It is commonly found in freshwater ponds, lakes, and slow-moving streams. This plant is a crucial part of the aquatic ecosystem and provides several benefits to the environment and wildlife.

Description and Characteristics

American pondweed has long, slender stems that can grow up to 2 meters in length. Its leaves are blade-shaped, with a smooth, glossy surface and a dark green color. The plant can grow both vertically and horizontally, and its leaves can be found floating on the surface of the water or submerged in the water column. It produces small, inconspicuous flowers that are arranged in a spike-like structure.

Benefits to the Environment

American pondweed provides several benefits to the aquatic environment. Firstly, it serves as a natural filter, absorbing excess nutrients and pollutants from the water. This helps to improve the water quality and reduce the risk of harmful algal blooms.

Secondly, it provides a habitat and food source for a variety of aquatic wildlife. Fish, birds, and other aquatic organisms rely on pondweed for shelter, breeding, and foraging. The dense patches of pondweed also provide protection for smaller aquatic creatures, such as invertebrates and tadpoles.

Lastly, American pondweed helps to stabilize the sediment on the bottom of the water body. The plant's roots penetrate deep into the sediment, anchoring it in place and preventing erosion.

Challenges and Management

Despite the benefits that American pondweed provides, it can also pose challenges in some cases. Invasive strains of pondweed can spread rapidly, outcompeting native aquatic plants and altering the natural balance of the ecosystem. This can have a negative impact on biodiversity and the overall health of the water body.

To manage these challenges, it is important to monitor the spread of invasive pondweed species and take measures to control their growth. This can include manual removal, the use of herbicides, or introducing natural predators or competitors to the ecosystem.

American pondweed is an important component of North America's aquatic ecosystems. It provides a variety of benefits to the environment and supports a diverse range of aquatic wildlife. While there are some challenges associated with invasive strains of pondweed, effective management strategies can help to maintain a healthy balance in the ecosystem.

More Information

One of the interesting aspects of American pondweed is its adaptability to different water conditions. It can thrive in both shallow and deep water, as well as in both still and flowing water. This makes it a versatile plant that can colonize many different types of aquatic habitats.

American pondweed also has some interesting adaptations that allow it to survive in low-light conditions. Its leaves are thin and flexible, which allows them to bend and twist to maximize their exposure to sunlight. Additionally, the plant can use a specialized form of photosynthesis called crassulacean acid metabolism (CAM) to store carbon dioxide and release it during the day when sunlight is available. This helps the plant to conserve water and maintain its growth even in low-light conditions.

In addition to its ecological benefits, American pondweed also has some practical uses. The plant has been used in traditional medicine to treat a variety of ailments, including respiratory and digestive issues. It is also sometimes used in the aquarium trade as a decorative plant.

Another interesting aspect of American pondweed is its role in carbon sequestration. Like all plants, pondweed takes in carbon dioxide from the atmosphere during photosynthesis and converts it into organic carbon compounds. When the plant dies and sinks to the bottom of the water body, this organic carbon is stored in the sediment. This process helps to remove carbon dioxide from the atmosphere, which can have important implications for mitigating climate change.

In addition to carbon sequestration, American pondweed also plays a role in nutrient cycling. It absorbs nutrients like nitrogen and phosphorus from the water, which helps to prevent eutrophication, a process where excess nutrients in the water can cause harmful algal blooms and other negative effects.

American pondweed is also an important food source for several aquatic organisms. Waterfowl, such as ducks and geese, feed on the plant's leaves and stems. Fish, including bass and bluegill, also rely on pondweed for food and shelter.

One challenge associated with American pondweed is the potential for it to become invasive. Non-native strains of pondweed can grow rapidly and outcompete native aquatic plants. This can have negative ecological effects, such as reducing biodiversity and altering the structure of the aquatic ecosystem. Therefore, it is important to monitor and control the spread of invasive pondweed species to maintain a healthy and balanced ecosystem.

American pondweed also plays an important role in improving water quality. It has the ability to absorb excess nutrients, such as nitrogen and phosphorus, from the water. These nutrients are often found in runoff from agricultural or urban areas and can lead to eutrophication, which can have negative impacts on aquatic ecosystems. By absorbing these nutrients, American pondweed can help to prevent eutrophication and improve water quality.

Furthermore, American pondweed can help to reduce erosion and stabilize shorelines. Its extensive root system can anchor sediment in place and prevent it from being washed away by currents or waves. This can help to reduce the loss of soil and nutrients from the surrounding land, which can have important implications for the health of the ecosystem.

Finally, American pondweed can also be used in ecological restoration efforts. It is often planted in wetlands and other degraded aquatic habitats to help restore ecosystem function and improve biodiversity. In these cases, pondweed can provide a natural and sustainable solution to ecosystem degradation.

In conclusion, American pondweed is an important and beneficial aquatic plant that provides a variety of ecological services. Its ability to absorb excess nutrients, stabilize sediment, and support aquatic wildlife makes it a crucial component of freshwater ecosystems. While challenges associated with invasive strains of pondweed do exist, careful management can help to maintain a healthy balance in the ecosystem and preserve the many benefits that American pondweed provides.

Distribution Map

Reproduced by kind permission of the BSBI.

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