Invasive pygmyweed threatens Lake District species
Pygmyweed has crowded out nine native species of Derwentwater in the Lake District and is posing a threat to wildlife in the New Forest, says the Royal Horticultural Society (RHS).
New Zealand Pygmyweed, also known as Australian swamp stonecrop or Crassula helmsii, forms a dense cover over the water’s surface, mitigating natural light and oxygen, causing potential harm to the wildlife below and obstructing navigation.
The Outdoor Swimming Society is urging wild swimmers to avoid transferring fragments of the plant to other lakes.
Originally brought to the UK in 1956, pygmyweed was marketed as an oxygenating plant used to decorate aquariums and sold in garden centres, but the RHS says it is now it is posing ‘serious threat to lakes and rivers’..
Pieces of the plant as small as a few milometers can grow into larger plants and it is known for its hardiness when trying to eradicate. The invasive species has been ruled illegal to grow in the wild and its sale was banned in 2014.