Pollen grain. Coloured Scanning Electron Micro- graph (SEM) of a pollen grain. Pollen grain size, shape and surface texture differs from one plant species to another. The outer wall (exine) of this pollen grain is highly sculpted and may assist in wind, water or insect dispersal. Such pollen sculpting variation between species is used by botanists to recognise plant species. Pollen grains contain the plant's male gametes which fertilise the female egg or ovule, with subsequent formation of plant seeds. Pollen also causes allergies and hay fever. Magnification: x2,000 at 6x6cm size.