Fremontodendron pollen grains. Coloured scanning electron micrograph (SEM). Fremontodendron, with the common names fremontia and flannel bush, is a genus of three known species of shrubs native to the Southwestern United States and Northwest Mexico but found commonly in gardens in the UK. Pollen grains are the male sex cells of a flowering plant. Their characteristic surface is used by botanists to recognise and classify plants. Pollen in plants is used for transferring male genetic material from the anther of a single flower to the stigma of another in cross-pollination. In a case of self-pollination, this process takes place from the anther of a flower to the stigma of the same flower. Magnification x 2200 at 10cm wide.