There are large clumps of bright green weed on the river. What is this weed?
This is a plant called floating pennywort (Hydrocotyle ranunculoides). Floating pennywort is an invasive species from North America. It was introduced as an ornamental pond plant but it has escaped into the wild. It is now established in many parts of the British Isles. The species was first recognised on the River Cam in 2007 but it may have been present in the main river or its tributaries before then. Floating pennywort can spread very quickly, out-competing native plant species and choking watercourses and ditches. It prefers nutrient-rich, slow-flowing ditches, lakes, ponds and canals. It has the potential for compromising flood control and navigation. The Centre For Ecology and Hydrology (CEH) has published an information fact sheet on their web pages at : http://www.ceh.ac.uk The weed can be eradicated using a combination of mechanical and chemical methods. Please report any sightings to the River Manager so that action can be taken to remove it. There are other non-native invas
