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Assorted pollen grains. Coloured Scanning Electron Micrograph (SEM) of pollen grains from a daisy flower (pink and spined), cherry blossom (orange) and hornbeam tree Carpinus sp. (green). Each species of flowering plant has pollen of a unique structure and shape. Here a variety of pollen grains is seen. Some are dispersed by the wind and others by insects such as bees. Windborne pollen may act as an allergen causing hay fever, itchy throat and inflamed eyes in allergic individuals. Magnification: x550 at 6x7cm size. (KEYSTONE/SCIENCE PHOTO LIBRARY/EYE OF SCIENCE)