Henrik Balslev

Ability of angiosperms to produce flowers and seeds for the sexual reproduction is important also in aquatic plants. Pollination in aquatic plants is facilitated by insects, wind, and water, however, pollen morphology related to the plant’s life forms and pollen dispersal are not well described. This study investigates pollen morphology of selected aquatic macrophytes. Plants were collected and preserved as dried specimens. Mature pollen grains of each species were separated from the anthers and then placed on glass slides and mounted with distilled water. Pollen shape and size were observed under a light microscope (LM). Number of apertures and exine ornamentation were examined using scanning electron microscope (SEM). Closely related plant species had similar pollen morphology. Among the 28 species studied, pollen size varied from small to very large (range 10–200 μm) and their shapes were prolate-spheroidal, prolate, oblate, suboblate, and oblate-spheroidal. Some species had inaperturate pollen grains; the remainders were monoaperture, triaperture or polyaperture. Both colpate and porate apertures were found. The pollen surfaces were echinate, fovelate, granulate, lophate, plicate, regulate, regulate-fovelate, reticulate, striate, and verrucate, respectively.