Slender stonewort  (Nitella gracilis)

This species has often been confused with the similar species Nitella mucronata var. gracillima. There have been confirmed records of slender stonewort from twelve sites, most of which are from western Britain (Cornwall, Shropshire, Ceredigion, Arfon, Cumbria, Kyle & Carrick and Sutherland) with one record from West Sussex. Just six of these areas (Ceredigion, Arfon, Kyle & Carrick and Sutherland) support recent records. It is likely that it may have been overlooked at a number of sites when it occurs in deeper water. Elsewhere, the species has a very wide distribution around the world, including Europe.

In Britain, this stonewort typically occurs in acidic lakes and pools, either in shallow water amongst other vegetation or in deeper water in large lakes where other vegetation is sparse. In the other parts of Europe it has been found in a greater variety of habitats, including brackish and alkaline waters.