Stems 10--30 cm. Leaves: stipules persistent, those on proximal portion of stem tightly clasping or slightly enlarged; 0.2--0.5 mm wide. Inflorescences: peduncles with flowers and/or fruits 4 cm or more apart. Fruits common. Flowering summer. Calcareous waters of ponds, lakes, and streams; 0--915 m; Greenland, N.W.T., Yukon; Alaska; Europe; Asiaasia. No specimens have been seen from British Columbia or Nunavut, but the subspecies is to be expected there.