A small native species of wet ground, similar to the slender club-rush (Isolepis cernua) but with a bristle-like projection of what appears to be the stem (but which is actually a bract) beyond the tiny flower spike; common and widespread across the whole of Northern Ireland.
All names: Isolepis setacea (L.) R.Br.; Scirpus setacea L.; Scirpus setaceus L.
NBN Atlas mapping: Species account : NBN Atlas UK Species Observations database
iNaturalist: Species account : iNaturalist World Species Observations database