False colour scanning electron micrograph of many pollen grains of a Colts foot, Tussilago farfara. Its outer wall (exine) consists of sharp spines; these get caught in an insects fur and are thus transferred when the insect goes to a different flower to feed. There are also germinal pores each capped with an operculum (lid). When the pollen grain, containing the male gametes, lands on the stigma of the flower, it germinates. A pollen tube grows out from one of these pores, down through the stigma, to the ovary. The male nuclei pass down the tube, fertilize the ovules & a seed is formed. Magnification: X236 at 35mm size.