Pasque flower pollen grains, coloured scanning electron micrograph (SEM). The genus Pulsatilla contains about 40 species of herbaceous perennial plants native to meadows and prairies of North America, Europe, and Asia. Pollen grains are the male gametes (sex cells) of a 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: x800 when printed at 10 centimetres wide.