Identification notes

Species varieties

• Fontinalis antipyretica subsp. antipyretica
• Fontinalis antipyretica subsp. gracilis

This is one of our easiest mosses to identify, forming wefts of robust parallel stems in running water. These can be several tens of centimetres long. The large leaves are arranged in three ranks and are folded along the midrib so that the two sides are pressed together forming a sharp keel. Trying to flatten a leaf by opening it out under a cover slip will cause it to split.

It is quite a variable plant with a number of infraspecific taxa described but we now recognise only the two above. Subsp. antipyretica has wide leaves, over a mm in width and often more than that in the eutrophic conditions that it can tolerate. Mid leaf cells are over 12µ wide. Subsp. gracilis is a smaller plant of acid water in the uplands, with leaves less than 1mm wide and mid leaf cells under 12µ. Fontinalis squamosa is smaller, darker, and with leaves that are concave but not keeled.

Capsules are uncommon and are immersed to emergent, with a very short seta.

Distribution in Great Britain and Ireland

Widespread in lowland Britain and Ireland, with subsp. gracilis being essentially an upland plant.