Coloured scanning electron micrograph (SEM) of bindweed (Calystegia sepium) pollen grains on the stigma surface. There is great variation in the size, shape and surface texture of pollen. The often highly-sculpted outer wall (exine) may help in pollen dispersal. Each pollen grain supplies a male gamete (male sex cell) that can fertilise the female gamete in an ovule that will develop into a plant seed. Field of view (horizontal field width) 196um