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Wolffia pollen are spherical with a diameter of ~16 microns, monoporate, and “echinate” with short spines (“spinules”) distributed randomly over the surface (Erdtman 1952, Kuoh et al. 2000).
Pollen of Wolffia and all Lemnaceae (duckweed family) are trinucleate, considered to be an advanced form derived from ancestral binucleate pollen in more primitive members of Order Arales. Many or most plants with trinucleate pollen are self-incompatable (Brewbaker 1967).
Brewbaker (1967) claims that underwater pollenation ocurs in Wolffia, although current observations of buoyant pollen call that into question. He also claims that the more primitive binucleate pollen are unable to germinate and grow in water or cultural soluti