Description: This pondweed was accidentally introduced into Ireland from North America. The first ever report of its occurrrence anywhere in Europe was at Waringstown, Co. Down in 1836. It subsequently spread at a tremendous rate across Ireland and Great Britain and is now extremely common in lowland lakes, ponds, canals and slow rivers.

The two sexes are on separate plants. The spread is entirely by vegetative means because only female plants occur in the British Isles, so seed-set is impossible.

All names: Elodea canadensis Michaux

Distribution Map from NBN: Elodea canadensis at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Elodea canadensis at iNaturalist World Species Observations database.