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Floating Pennywort

Hydrocotyle ranunculoides

Hydrocotyle ranunculoides Hydrocotyle ranunculoides
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Contents

Plant Profile

Flowering Months:
JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC
Order:
Apiales
Family:
Araliaceae (Ivy)
Also in this family:
Common Ivy, False Castor Oil Plant, Irish Ivy, Marsh Pennywort, Persian Ivy
Type:
Flower
Life Cycle:
Perennial
Maximum Size:
20 centimetres tall
Habitats:
Ditches, ponds, water.

Flower:
֍
Green, 5 petals
 
Tiny, pale green-white, 5 petals, in umbels. Not often seen in flower.
Fruit:
Elliptical or round fruit, up to 3mm long. Flattened and lightly ribbed, divided into two halves.
Leaves:
Rounded kidney-shaped leaves, growing compactly together and densely covering the water upon which it floats. Leaf margins are smooth or scalloped with 3 to 7 lobes.
Other Names:
Buttercup Pennywort, Creeping Marsh Pennywort, Floating Marsh-pennywort, Water Pennywort.
Frequency (UK):
Occasionally seen  

Other Information

Summary

Hydrocotyle ranunculoides, also known as floating pennywort or creeping marsh pennywort, is a perennial aquatic herb that is native to North America and Europe. It typically grows to be about 20cm tall and has small, white or greenish-white flowers that bloom in the summer. The leaves are round, glossy and typically a bright green color. It typically grows in shallow waters, such as marshes, ponds, and ditches. It can also be found along the margins of slow-moving streams and rivers. It can quickly become invasive and can form dense mats in water bodies, which can have negative effects on native aquatic plants and animals. It's also known for its medicinal properties and it has been traditionally used to treat a variety of ailments.

Blog

Floating pennywort, also known as Hydrocotyle ranunculoides, is a highly invasive aquatic plant species that is native to North America. It is an aggressive species that can quickly dominate waterways and outcompete native plant species, causing significant ecological damage.

Appearance and characteristics

Floating pennywort is a herbaceous perennial that can grow up to 20cm in height. Its leaves are round, green and can be up to 20cm in diameter. The plant forms a dense mat on the water surface, which can cover large areas of waterways, hindering navigation and causing problems for recreational activities such as fishing and boating.

Invasive behavior

Floating pennywort is a highly invasive species that can rapidly spread and establish itself in new waterways. It reproduces both vegetatively and sexually, and each plant can produce up to 50 new plants per year. The plant can detach itself from the parent plant and float downstream, allowing it to establish new colonies in different areas.

Ecological impacts

Floating pennywort is a serious threat to aquatic ecosystems. The dense mats it forms on the water surface can block sunlight from reaching other aquatic plants, reducing the oxygen levels in the water and causing significant ecological damage. It can also outcompete native plant species, reducing biodiversity and altering the structure and function of the ecosystem. The dense mats of the plant can also cause problems for fish and other aquatic animals, as they can become trapped in the mats or lose access to their natural habitats.

Management

Preventing the spread of floating pennywort is crucial in managing its impact. People should take care not to introduce the plant to new waterways by cleaning their boats, equipment and clothing after use in infested waters. Once established, the plant can be difficult to remove, and a combination of control measures may be required, including physical removal, herbicide treatment, and biological control using specialist herbivores.

Floating pennywort is an aggressive and highly invasive plant species that poses a significant threat to aquatic ecosystems. Preventing its spread and implementing effective management strategies are crucial in minimizing its impact on the environment.

More Information

Floating pennywort is a plant species that is native to North America, but it has been introduced to other parts of the world, including Europe, Asia, and Africa. In these new areas, it has become an invasive species, causing significant ecological damage and economic losses. For example, in the UK, it has been estimated that the plant causes around £23 million in damages per year.

The rapid spread and establishment of floating pennywort are partly due to its ability to adapt to a wide range of environmental conditions, including temperature, pH, and nutrient levels. It can grow in both still and flowing water, from shallow ponds to deep lakes and rivers. It can also survive in low-light conditions and tolerate water pollution, making it a formidable competitor against native aquatic plants.

The management of floating pennywort requires a coordinated effort from different stakeholders, including government agencies, waterway authorities, and local communities. In many cases, physical removal of the plant is the most effective method of control, but it can be labor-intensive and costly. Herbicide treatment is another option, but it can have unintended consequences for non-target species and water quality. Biological control using specialist herbivores, such as weevils, has been successful in some areas, but it requires careful monitoring and evaluation to ensure that it does not have adverse effects on native species.

The impact of floating pennywort on the environment is not limited to aquatic ecosystems. The plant can also have significant economic and social impacts, affecting industries such as agriculture, tourism, and water management. For example, the dense mats of the plant can clog water intakes, irrigation systems, and hydropower turbines, leading to operational and maintenance costs.

Furthermore, floating pennywort can also affect recreational activities, such as fishing, boating, and swimming. The dense mats can make it difficult to access waterways and reduce the aesthetic value of the environment, negatively affecting the quality of life of nearby residents.

The prevention and control of floating pennywort require a long-term approach that considers the complexity of the problem and involves the participation of all stakeholders. A coordinated effort between governments, non-governmental organizations, scientists, and local communities is essential to identify the most effective control methods and implement them in a sustainable and cost-effective manner.

One promising approach is the use of citizen science to monitor the spread of the plant and assist in its control. Citizen science involves the participation of volunteers in scientific research, data collection, and analysis. In the case of floating pennywort, citizen science can help to identify new infestations, monitor the effectiveness of control measures, and raise public awareness of the issue.

In conclusion, the impact of floating pennywort on the environment and human activities is significant and requires a comprehensive and collaborative approach to manage. Through the involvement of all stakeholders, including citizens, we can work towards preventing the spread of this invasive species and protecting the health and well-being of our ecosystems and communities.

Quick Facts

25 Facts About Floating Pennywort:

  1. Floating pennywort is an invasive aquatic plant species that is native to North America.
  2. The scientific name for floating pennywort is Hydrocotyle ranunculoides.
  3. The plant can grow up to 20cm in height, with leaves up to 20cm in diameter.
  4. Floating pennywort forms a dense mat on the water surface, hindering navigation and causing problems for recreational activities.
  5. The plant reproduces both vegetatively and sexually, with each plant producing up to 50 new plants per year.
  6. Floating pennywort can detach itself from the parent plant and float downstream, establishing new colonies in different areas.
  7. The dense mats formed by floating pennywort can block sunlight from reaching other aquatic plants, reducing oxygen levels in the water.
  8. The plant can outcompete native plant species, reducing biodiversity and altering the structure and function of the ecosystem.
  9. The dense mats can also cause problems for fish and other aquatic animals, trapping them or losing access to their natural habitats.
  10. Floating pennywort is highly adaptable, growing in a wide range of environmental conditions and waterways.
  11. The plant has been introduced to Europe, Asia, and Africa, where it has become an invasive species.
  12. In the UK, floating pennywort is estimated to cause around £23 million in damages per year.
  13. Physical removal of the plant is the most effective method of control, but it can be labor-intensive and costly.
  14. Herbicide treatment is another option, but it can have unintended consequences for non-target species and water quality.
  15. Biological control using specialist herbivores, such as weevils, has been successful in some areas.
  16. Preventing the spread of floating pennywort is crucial in managing its impact.
  17. People should take care not to introduce the plant to new waterways by cleaning their boats, equipment, and clothing after use in infested waters.
  18. Floating pennywort can affect industries such as agriculture, tourism, and water management.
  19. The dense mats can clog water intakes, irrigation systems, and hydropower turbines, leading to operational and maintenance costs.
  20. Floating pennywort can also affect recreational activities, such as fishing, boating, and swimming.
  21. Citizen science can help to monitor the spread of the plant and assist in its control.
  22. A coordinated effort between governments, non-governmental organizations, scientists, and local communities is essential to manage the impact of floating pennywort.
  23. The long-term prevention and control of floating pennywort require sustainable and cost-effective measures.
  24. The participation of all stakeholders, including citizens, is crucial to identify the most effective control methods and implement them in a sustainable manner.
  25. The prevention and control of floating pennywort are essential to protect the health and well-being of our ecosystems and communities.

Floating pennywort is a highly invasive aquatic plant species that poses a significant threat to the environment and human activities. The plant can grow rapidly, reproduce quickly, and adapt to a wide range of environmental conditions, making it a formidable competitor against native aquatic plants. The dense mats it forms on the water surface can block sunlight from reaching other aquatic plants, reducing oxygen levels in the water, and causing significant ecological damage. Physical removal, herbicide treatment, and biological control are the most common methods of control, but preventing the spread of the plant is crucial in managing its impact. The participation of all stakeholders, including citizens, is essential in the long-term prevention and control of floating pennywort to protect the health and well-being of our ecosystems and communities.

Video

Floating Pennywort filmed at the side of the Leeds and Liverpool Canal in Wigan on the 7th August 2022.

 

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Distribution Map

Reproduced by kind permission of the BSBI.

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