"Futo-hirumushiro" (Potamogeton fryeri) belong to Potamogetonaceae (the Pondweed family). It is a perennial herb that is native to Japan, as well as the Kuril Islands, Sakhalin and the Korean Peninsula. This herb grows in acidic ponds and swamps, it bears submersed leaves and floating leaves on the stems. The submersed leaves are little, lanceolate, and the floating leaves are elliptic with wavy edges. The small yellowish-green flowers bloom in the axilary spikes of floating leaves from April to August.