Greater Water-moss - Fontinalis antipyretica

This is our largest aquatic moss, with shoots 5 to 8 mm wide and often exceeding 15 cm in length. The leaves are 4 to 5 mm long and strongly folded inwards along the midline, with the fold-line forming a prominent keel. The shoots are usually 3-sided, with the keels forming the angles and the overlapping halves of adjacent leaves forming the sides. The leaf lacks a nerve (though it is not easy to unfold the keel and demonstrate this) and its tip is bluntly pointed and untoothed. Capsules are very uncommon, and almost hidden amongst the leaves, occurring only on plants which
have undergone a period of exposure above the water.

F. antipyretica grows in a wide range of still, slowly or rapidly flowing water bodies, including lakes and ponds, canals, streams and rivers. Plants are usually attached to stones, rocks or waterside trees, but sometimes occur in loose masses on the bottom of shallow, still waters. It tolerates a wide range of water quality, but is usually replaced by F. squamosa in the most acidic and nutrient-poor waters. It tolerates periods of emersion and may be found above the water at times when levels are low; it is also frequent around turloughs (seasonal lakes over limestone) in Ireland.

Widespread and frequent in Britain.
 

Frequent in Leicestershire and Rutland.