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Larch pollen grains. Light micrograph of pollen grains from the European larch tree, Larix decidua. The size, shape and surface texture of these pollen grains is unique in each plant species. The sculptured outer wall (or exine) of the grain plays a role in it's dispersal by wind, water or insects. Pollen grains contain the male gametes of the plant which fertilize the female egg (or ovule) to form the plant seed. Pollen also causes allergies and hay fever. Magnification: x85 at 35mm size. (KEYSTONE/SCIENCE PHOTO LIBRARY/ASTRID & HANNS-FRIEDER MICHLER)