Canadian Waterweed, Elodea canadensis, and Nuttall's Waterweed, Elodea nuttallii, are aquatic invasive non-native species now found throughout the UK. They live in freshwater as perennial, submerged waterweeds and although they produce small white flowers they only reproduce vegetatively as all plants are female. Canadian Waterweed was first found in Britain in 1842, whilst Nuttall's Waterweed, which is found in more nutrient-rich water, was not recorded as naturalised in Britain in 1966.
The invasion of the freshwater lochs of the islands by invasive alien aquatic plants can have serious detrimental effects on their biodiversity and economic value. Both species of Elodea have been recorded here and it is importance that their distribution is monitored. Their spread can be impeded by ensuring that everyone who uses the lochs for follows the Check-Clean-Dry biosecurity guidance.
Information and Identification Sheets:
Canadian and Nuttall's Waterweeds
SNH Species Action Framework: Invasive non-native plants associated with fresh waters. A Guide to their identification