Pistil of a flower. Coloured scanning electron micrograph (SEM) of part of the pistil of a cinquefoil flower (Potentilla sp.). The pistil is the female reproductive part of a flower, comprising one or more carpels. Each carpel is made up of a stigma (tip, dark orange) borne on a style (shaft, light orange). 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 fertilises the ovum there, forming a seed.