Arnica pollen grain. Coloured scanning electron micrograph (SEM) of a chamisso arnica (Arnica chamissonis) plant's pollen grain. The outer wall (exine) of this pollen grain is highly sculpted to aid the dispersal of the pollen grain. A flowering plant produces many pollen grains which need to be dispersed. This dispersal may happen as the spiky exine sticks to a pollinator such as a bee. Each pollen grain contains a male gamete (reproductive cell) that is intended to fertilise the ovule or egg (female gamete) of an arnica plant, and form a seed for a new plant. Magnification: x2670 when printed 10cm wide.