Origin: North America
UK Distribution: Widespread
Habitat: Still or slow moving water
How was it introduced? Introduced as an ornamental plant in the 19th century
How does it reproduce? Solely by vegetative means
Floating pennywort (Hydrocotyle ranunculoides) is native to North America. Introduced widely across Europe as an ornamental pond species, pennywort has now become established in the wild with serious economic and ecological consequences.
This aquatic invasive can grow up to 20 cm a day producing 70 kg of wet weight per square metre. This high growth rate means pennywort can quickly cover a water body, smothering the wildlife underneath, blocking out sunlight and reducing oxygen levels.
Wandle distribution: The upstream source of pennywort is currently known to be Wilderness Island in Sutton. From here, the plant has spread and established itself in most slow moving sections of the Wandle downstream all the way to Wandsworth. To tackle pennywort, we are focusing our efforts on the upstream source with a mixture of hand pulling and herbicide application. We have also been conducting a trial at Watermeads Nature Reserve to find the most effective method for clearing a large infestation in still water.
Think you have floating pennywort on your land? If you think you may have pennywort on your land, please take a picture and send it to us at email@example.com. We can ID the plant and then provide you with guidance on how to control this species.