Pollination. Colored scanning electron micrograph (SEM) of pollen grains (pink) on the stigma of a flower. The stigma is the sticky tip of a carpel, one or more of which make up the pistil (the female reproductive part of a flower). Each carpel comprises a stigma, a style (the projection between stigma and ovary), and an ovary containing eggs (not seen). Pollen, the male sex cells of a flowering plant, lands on the stigma and burrows down through the style to reach the ovary at the style's base. It then fertilizes the ovum there, forming a seed.