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Floating pennywort

(Hydrocotyle ranunculoides)

Floating pennywort © Tim Pankhurst/Plantlife

Floating pennywort © Tim Pankhurst/Plantlife


Banned From Sale after April 2014. A non-native invasive plant.

This very popular and widely available aquatic plant forms dense mats of rounded leaves that float across the water surface. It is most common in the wild in south-east England but is appearing more often in the west, the midlands and in Wales. It has been sold incorrectly labelled as ‘marsh pennywort’, the common name for Hydrocotyle vulgaris, a native British species that is not invasive. It may also be sold as ‘water pennywort’.

Habitat

Lakes, ponds and other water-based habitats.

What's the problem

Floating pennywort causes a range of problems including changing the availability of oxygen in the water, threatening fish and invertebrates, choking drainage systems and crowding our native water plants.

Rapid Risk Assessment

***** Critical Risk

Plantlife's position

Plantlife campaigned to have this species banned from sale. As of April 2014, in England and Wales, it will be. This species is also listed on Schedule 9 of the Wildlife and Countryside Act in England and Wales therefore, it is also an offence to plant or otherwise cause to grow these species in the wild.

Removing floating pennywort

Floating pennywort is difficult to control due to its rapid growth rates (up to 20cm per day!) and its ability to re-grow from a small fragment. Regular cutting from May-October will prevent complete dominance and so help manage this plant. Cut material needs to be removed from the water immediately. Hand pulling (or spot chemical treatment) should follow cutting to reduce re-growth. Pulling is likely to work best on small infestations rather than larger areas. Chemical treatment should only be used at the end of the growing season when all other plants have died back.