Pollen grain. Coloured scanning electron micrograph (SEM) of a pollen grain from a lily, (Lilium sp.). Pollen grain size, shape and surface texture differ from one plant species to another. The outer wall (exine) of the pollen in many plant species is highly sculpted which may assist in wind, water or insect dispersal. This pollen sculpting is also used by botanists to recognise plant species. Pores in the pollen wall help in water regulation and germination. Pollen contains the plant's male gametes. These fertilise the eggs or ovules, initiating formation of plant seeds. Magnification unknown.