Alien species

Alien species

Himalayan Balsam

This species tends to grow in damp areas. This annual is becoming a real problem on the River Derwent from Borrowdale to Bassenthwaite Lake.

An elegant, tall and very attractive plant, the balsam crowds out other native species and also scatters thousands of seeds - a single plant can spread over 6,000 seeds.

Once the seeds for the following year have been spread, the plant dies back over the winter. Having crowded out native grasses it then leaves bare soil, which makes riverbanks or lake shores very prone to erosion in winter storms.

New Zealand pigmyweed - Crassula helmsii

This plant is threatening the Lake District's wildlife, especially Luronium natans. It's a tough invader, which grows all year and out-competes our native plants.

It grows rampantly on damp ground, lakeshores, and in shallow and deep water. New Zealand pigmyweed is very hard to kill and just a 1 cm piece can grow to dominate a wetland.

Because New Zealand pigmyweed can be spread by footwear, fishing tackle, boat propellers and boat trailers precautions need to be taken to stop its spread.

It is essential lake users remove any plants or plant remains from equipment before leaving the lake.