False-colour scanning electron micrograph (SEM) of a pollen grain of the passion flower, Passiflora caerulea. The spherical grain has a diameter of 50 micrometres & looks rather like a tennis ball. Its outer wall is highly sculptured, & is divided by three wide germinal furrows. When the pollen grain, containing the male gametes, lands on the stigma of the flower, it germinates. A pollen tube grows out of one of the germinal furrows. Passion flowers provide copious nectar, & are insect- pollinated. Magnification: x45 at 35mm size.