Sunflower pistil. Coloured scanning electron micrograph (SEM) of a sunflower (Helianthus annuus) pistil. Pollen grains (round and spiky, orange) are seen on the pistil. Pistils hold a plant's female reproductive structures. They contain one or more carpels, which, in turn, contain a stigma, style and an ovary. Within the ovaries are the ovules, the female gametes (sex cells). The ovaries are fertilised by pollen grains, the male gametes. Magnification: x85 when printed at 10 centimetres wide.