This is a very pretty member of the Hypericaceae or St John’s-wort family which is not very widespread in Ireland, growing mainly in Munster and Connemara. It has small yellow 5-petalled flowers (12-20mm across) which has erect, sepals, each sepal being dotted along its margins with tiny red beads. The flowers are borne in small clusters from June to September. The grey-green leaves are round and softly hairy and they clasp the stems at their base. They have small translucent dots.
Forming dense, low mats in damp, acid places, Marsh St John’s-wort creeps along, rooting at the lower nodes on its stems. It is a native plant species which grows in pond margins and in bogs and marshes.
I first saw this attractive species in ‘captivity’ in 2015, when I also photographed it. It was in the pond of a good friend who gave me a small piece for my own pond and I’m delighted to report that it took root.
If you are satisfied you have correctly identified this plant, please submit your sighting to the National Biodiversity Data Centre