This perennial is found throughout the country in bogs and ditches, by streams and other damp places, this is a very tiny, straggly wildflower which barely exceeds 25 cm high. It has square stems, unstalked, oval, blue-green leaves and its small white flowers (5–6 mm across) have widely separated, deeply divided, pointed petals. The sepals are longer than the petals which is a helpful means towards identification. It flowers from May to August, is a native plant which was formerly known as Stellaria uliginosa, and it belongs to the Caryophyllaceaefamily.
My first record of this plant is in 2006 near Laragh, Co Wicklow at which time I also photographed it.
If you are satisfied you have correctly identified this plant, please submit your sighting to the National Biodiversity Data Centre