Periwinkle flower pollination. Coloured scanning electron micrograph (SEM) of a grain of pollen (lower left) on the stigma of a periwinkle flower (family Apocynaceae). The pollen grain, which contains male genetic material, has become trapped by the stigma's papillae (hair-like structures, pink). The stigma is part of the female reproductive structure (pistil), which is formed from one or more carpels. Each carpel consists of a stigma, a style and an ovary (not seen). If the female sex cells (ovules) in the ovary become fertilised by the pollen's genetic material, the carpel may ripen to produce a fruit containing seeds. Magnification: x70 at 6x7cm size.