Local, forming loose to dense patches in rocky, cobbly substrate. In shallow water to ~6 inches deep, and stranded up to ~12 inches above the present water level, which is down ~18 inches from the early season high mark (due to an extended drought). Full sun to partial shade of Thuja occidentalis and Picea mariana growing on the adjacent upland.
Associates include Myrica gale, Equisetum fluviatile, Lysimachia terrestris, Osmunda regalis.