Colored SEM of pollen from a primrose, Primula sp 

Primrose pollen. Colored scanning electron micrograph (SEM) of pollen grains (pink) from a primrose flower (Primula vulgaris). The pollen shows the round, sculpted protein coat characteristic of primroses. Pollen is produced by the male sex organs in primrose flowers and dispersed by insects to the female sex organs where the eggs are fertilized. Species of the Primula genus have evolved so that two types of hermaphrodite flower are produced and an individual plant only produces one type. The difference in structure between the two flower types favors cross-pollination. Self-pollination tends to produce less viable seeds.