Coltsfoot pollen. Coloured Scanning Electron Micrograph (SEM) of pollen grains on the stigma of a Coltsfoot flower Tussilago farfara. The pollen is coloured red. The stigmatic surface is dark brown on top of the tubular style (light brown). Each pollen grain has sharp spines which get caught on an insect and are thus transferred when the insect goes to a different flower to feed. When the pollen grain, containing the male gametes, lands on the stigma of the flower, it germinates. A pollen tube grows out and down through the stigma, to the flower ovary. Male gametes pass down the pollen tube to fertilize the ovules (eggs). Magnification: x65 at 6x6cm size.