A tall rhizomatous perennial herb of standing or flowing fresh water, in conditions ranging from eutrophic and base-rich to oligotrophic and base-poor. Substrates include silt, clay, peat or gravel. It occurs in ponds, lakes, canals, dykes and slow moving rivers, usually in water 0.3-1.5 m deep, but can also be found in deeper water. Generally lowland, but reaching 405 m at Dock Tarn (Cumberland).
The distribution of S. lacustris is very similar to that shown in the 1962 Atlas, where it was mapped as `all records`, but there have been local losses in S.E. England.
Eurosiberian Wide-temperate element.