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Long-stalked Pondweed

Potamogeton praelongus

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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 flowers spikes, up to 20cm tall. 15 to 20 flowers per spike. The 4 petals are actually sepals and there are no true petals.
Large, brownish, roundish fruits. The dimension of the fruits are approximately 3x5cm.
The green, net-veined leaves are alternate with whitish stipules clasping their stems. They are lanceolate in shape, blunt-tipped and unstalked. Long-stalked Pondweed is Britain's only wavy-leaved Pondweed and it often has zigzagged stems. Often seen in deep, limy water, in such places as rivers and lakes. Perennial.
Other Names:
Whitestem Pondweed, White-veined Pondweed.
Frequency (UK):
Rarely seen  

Similar Species

Other Information


Potamogeton praelongus, also known as white-veined 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 are long, thin, and typically float on the water's surface, they are lanceolate in shape, with smooth edges and characteristic white veins. The stems are long, thin, and 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.


Long-stalked Pondweed, scientifically known as Potamogeton praelongus, is a perennial aquatic plant found in freshwater environments throughout the world. It belongs to the family Potamogetonaceae and is commonly known as the slender pondweed due to its long, thin stems.


Long-stalked Pondweed is a submerged aquatic plant that typically grows in still or slow-moving water bodies such as ponds, lakes, and slow-moving streams. It has long, slender stems that can reach up to 2 meters in length and grow from a rhizome. The leaves are narrow and elongated, measuring up to 10cm in length and 1cm in width, with a slightly wavy margin. The leaves are arranged alternately along the stem and are attached to the stem by a long stalk. The plant does not have true roots but instead has a root-like structure called a rhizome, which anchors it to the substrate.

Habitat and Distribution

Long-stalked Pondweed is widely distributed across the temperate regions of the world, including Europe, Asia, North America, and Australia. It prefers freshwater environments with a pH range of 6.0 to 8.0 and is typically found in still or slow-moving waters such as ponds, lakes, and slow-moving streams.

Ecological Importance

Long-stalked Pondweed plays an essential role in freshwater ecosystems by providing food and habitat for a variety of aquatic animals, including fish, invertebrates, and waterfowl. The plant also helps to maintain water quality by absorbing excess nutrients, stabilizing sediments, and oxygenating the water column.

In addition to its ecological importance, Long-stalked Pondweed has been used for centuries for medicinal purposes. It is believed to have anti-inflammatory and analgesic properties and has been used to treat a variety of ailments, including rheumatism, arthritis, and gastrointestinal disorders.

Threats and Conservation

Like many aquatic plants, Long-stalked Pondweed is threatened by a variety of factors, including habitat loss, pollution, and climate change. Invasive species such as Eurasian Watermilfoil (Myriophyllum spicatum) can also outcompete Long-stalked Pondweed for resources, leading to its decline in some areas.

Conservation efforts aimed at protecting freshwater ecosystems and reducing the impacts of human activities on these systems can help to preserve Long-stalked Pondweed and other aquatic plants. These efforts include measures such as wetland restoration, nutrient management, and the control of invasive species.

Long-stalked Pondweed is a vital component of freshwater ecosystems, providing food and habitat for a variety of aquatic animals and helping to maintain water quality. Despite its ecological and medicinal importance, Long-stalked Pondweed and other aquatic plants are threatened by human activities, including habitat loss, pollution, and the introduction of invasive species. Conservation efforts aimed at protecting freshwater ecosystems can help to preserve these valuable resources for future generations.

More Information

Long-stalked Pondweed is an interesting plant that has been studied for its ecology, morphology, and genetics. It is a diploid plant with a chromosome number of 2n=26, and it reproduces vegetatively via its rhizomes or sexually through the production of flowers and seeds.

The plant is known to exhibit some interesting morphological adaptations to its aquatic environment. For example, its narrow leaves and long stems help to reduce drag and resistance, allowing it to move easily in water. Additionally, its elongated leaves allow it to maximize its surface area for photosynthesis, which is essential for its survival.

In terms of its ecological role, Long-stalked Pondweed is known to be an important food source for a variety of aquatic animals, including waterfowl, fish, and invertebrates. Its leaves are rich in nutrients and are often used as a substrate for the attachment of small organisms such as algae and diatoms.

Despite its ecological importance, Long-stalked Pondweed is also considered a nuisance plant in some areas, where it can form dense mats that interfere with recreational activities such as boating and fishing. Control measures such as herbicides and mechanical removal are often used to manage its growth.

Long-stalked Pondweed is also known to exhibit phenotypic plasticity, which allows it to adapt to different environmental conditions. For example, it can adjust its leaf morphology and physiology in response to changes in light, temperature, and nutrient availability. This plasticity makes it a particularly interesting species for studying the effects of environmental stress on aquatic plants.

In addition to its ecological and scientific importance, Long-stalked Pondweed also has cultural and economic significance. In some regions, it is used for traditional medicine, as well as for food and livestock feed. It is also cultivated as an ornamental plant for use in aquariums and water gardens.

Long-stalked Pondweed is a fascinating plant with many important ecological, scientific, cultural, and economic roles. As we continue to study and appreciate this plant, it is essential that we work to protect its habitats and preserve its diversity for future generations. Through conservation efforts and responsible management practices, we can ensure that Long-stalked Pondweed and other aquatic plants continue to contribute to the health and well-being of our freshwater ecosystems.

Long-stalked Pondweed also has the potential to be used in phytoremediation, which is the use of plants to remove pollutants from the environment. Studies have shown that it can effectively absorb and accumulate heavy metals such as copper, zinc, and lead, as well as nutrients such as nitrogen and phosphorus. This makes it a promising candidate for cleaning up contaminated water bodies.

In terms of its genetic diversity, Long-stalked Pondweed has been found to exhibit high levels of genetic variation within and among populations. This genetic diversity is essential for the plant's adaptation to changing environmental conditions, as well as for its resilience to stressors such as pollution and climate change.

Finally, it is worth noting that Long-stalked Pondweed is just one of many species of aquatic plants that play important roles in freshwater ecosystems. Other species such as water lilies, watermilfoils, and cattails also contribute to the health and diversity of these ecosystems. By protecting and preserving these important plant communities, we can ensure the long-term health and sustainability of our freshwater resources.

Distribution Map

Reproduced by kind permission of the BSBI.

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