Environmental charity Keep Britain Tidy, in partnership with the Environment Agency, has launched its #PennywortAlert scheme for 2023 as it urges the public to report sightings of the harmful aquatic weed, floating pennywort, on waterways. Floating pennywort can grow up to an astonishing 20cm per day in late summer. It forms dense mats of kidney-shaped leaves on the water’s surface, depleting oxygen levels, blocking out vital sunlight for our native aquatic plants and, ultimately, threatening fish, invertebrates, insects and our wider native ecosystems.
The weed is also a menace for river users – stopping angling, water sports and river and canal navigation, often clogging up boat propellers. It can also block key river infrastructure, including weirs, sluices and pumps, which can lead to flooding.
The weed has spread rapidly into UK waterways since it was introduced into this country from America in the 1980s as an ornamental garden pond plant. It has been banned from sale since 2014 in the UK and it is now against the law to cause floating pennywort to grow in the wild. Floating pennywort costs millions to public and private organisations, requiring physical removal from the water with machinery, which is costly and time-consuming.
“Damage to our waterways caused by floating pennywort is well documented, as is the knock-on effect to the communities of people who live near and enjoy our rivers for recreation,” says Lynsey Stafford, who manages Keep Britain Tidy‘s RiverCare & BeachCare programme in the East of England. “It is highly invasive and incredibly harmful to our environment.”