Wallflower pollen grains. Coloured scanning electron micrograph (SEM). Erysimum (wallflower) is a genus of flowering plants in the botanical family Brassicaceae, that includes about 180 species, both popular garden plants and many wild forms. 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.