THE FLORAL BIOLOGY OF GROENLANDIA-DENSA (L) FOURREAU (POTAMOGETONACEAE)

The floral biology of the obligately aquatic plant species Groenlandia densa (L.) Fourreau was studied. It is effectively pollinated (1) in air above the water surface (anemophily), (2) at the water surface where the stigmas can pick up pollen grains directly from the surface of the water (epihydrophily), or (3) underwater with wet stigmas (hypohydrophily). Underwater, the pollen grains are associated with the air-water interface of bubbles, but they may be positioned on both sides of this interface. The breeding system is almost entirely autogamous with self-fertilization; a slight degree of proterogyny may permit some outbreeding. © 1990.