Riccia huebeneriana Violet Crystalwort

This is a flat green liverwort that often shows violet or purplish tints. It grows on nutrient-poor muds on the edges of ponds, lakes and reservoirs that are exposed when water levels fall.

Trampling of mud by cattle seems to assist it, but stabilisation of water levels (for recreational or amenity purposes) and water pollution by over-enrichment from farm fertilisers are both current threats.