Isoetes lacustris

Isoetes lacustris, the lake quillwort or Merlin's grass, is a boreal quillwort native on both sides of the northern Atlantic Ocean. In Europe, it is distributed from Poland west to northeastern France, throughout Scandinavia, the west and north of the British Isles, the Faroe Islands and Iceland. Further south, isolated populations occur in the glacial lakes of the Pirin mountain range in Bulgaria.