Mallow pollen grain. Light micrograph (LM) of a mallow flower (Lavatera sp.) pollen grain (yellow). The grain has a highly sculptured outer wall (exine). This, together with a coating of oil, causes the grains to stick each other and to pollinating insects, aiding its dispersal. A grain of pollen contains a male gamete that is intended to fertilise an ovule (female gamete), and initiate the formation of a seed. Magnification: X251 when printed 10 centimetres wide.