Morphological differences between anemophilous and entomophilous pollen

In order to provide a palynological guide for the identification of insect-carrying pollen grains, we studied the pollen grains of 10 anemophilous species and 10 entomophilous species in the Beijing urban area using light and scanning electron microscopies. We found that anemophilous pollen grains are small, spheroidal, or oblate spheroidal, while entomophilous pollen grains are medium and oblate. Comparison of the exine thickness and surface ornamentation showed that anemophilous pollen grains have significantly thinner exine and smoother surface ornamentation than entomophilous pollen grains. The results also revealed pollen characteristics adaptive to different pollination types. Overall, our study indicated that pollen morphology might be helpful for preliminary identification of anemophilous and entomophilous pollen.