BOATERS have been warned not to be complacent and let an 'invasive and destructive' plant gain a hold in the river Thames.

Pennywort is usually more common in the summer months but the Environment Agency wants anyone braving the cold and going out onto the river to keep a look-out for fresh outbreaks.

Large blooms of the plant affect the oxygen content of rivers, reduce biodiversity, can damage important habitats and potentially increase flood risk.

In July, the agency reported that more than 63 tonnes of Pennywort had been removed from the Thames, thanks in part to sightings being reported by those who use the river.

The plant is characterised by its distinctive kidney-shaped leaves and long stalks. It often grows in dense patches, forming a thick mat on the water surface.

Daryl Buck said: “The Environment Agency and our local partners have been working hard to manage and monitor the spread of Floating Pennywort in 2018 and because of this good work we have had to remove significantly less Floating Pennywort than in 2017.

"This reduced growth shows that we are starting to get the spread of this invasive plant under control but we are not getting complacent and we know that, with everyone’s help, we will need to continue our efforts for several years to come”