Floating Pennywort (Hydrocotyle ranunculoides)
Known commonly as water pennywort, floating pennywort, or floating marshpennywort. 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, Wales and also Ireland.
It can be commonly found on lakes, ponds and other water-based habitats.
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.
Floating pennywort is difficult to control due to its rapid growth rates 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.