Water Lobelia is an aquatic perennial of the Campanula family. The flowers are a pale mauve and hang elegantly on a slender stalk, well above water level. The leaves are in a completely submerged basal rosette.
The plant roots in acid shallow water. It is frequently found in turf margin lakes from Kerry northwards, through Clare, Galway and Mayo to Donegal, and is common in most of Achill Island's lower-level lakes. It is rare in the rest of the country. Lobelias are named after Mathias de l'Obel, the distinguished Flemish botanist who studied in the 16th century. The flowers appear in July and August.
Water Lobelia is found in lakes in north-west Britain and in north-west Europe.