FLORA OF ICELAND elements: Potamogeton perfoliatus, Perfoliate Pondweed, Hjartanykra

Potamogeton perfoliatus; The Perfoliate Pondweed can form submersed stems up to 1m long.
  - They only have submersed leaves which are rather broad and short: obovate to elliptic. At the base they are cordate, clasping the stems. They are dark green in color. The stems are quite straight. The stipules drop soon.
  - The many flowers are on a spike of about 2cm long and ½cm wide. The inflorescenses are on stems of about (more or less) 5cm protruding above the water suraface. The flowers lack a perianth.
  - It is found in lakes and ponds prefering those that are partially fed by thermal water.
  - It is a member of the Potamogetonaceae, the Pondweed family The Icelandic name for this species is Hjartanykra.