Bellflower pistil. Coloured scanning electron micrograph (SEM) of the pistil of a bellflower plant (Campanula sp.). The pistil is the female reproductive part of a flower. In this plant it consists of fused carpels. The carpels contain the ovules (female gametes). Pollen grains (the male sex cells) land on the stigma at the top of the pistil and grow a tube down into the carpel in order to fertilise the flower.