Coloured scanning electron micrograph (SEM) of bindweed (Calystegia sepium) pollen grain on leaf 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) 121um.