Cerastium pollen. Coloured scanning electron micrograph (SEM) of a pollen grain of cerastium. Cerastium is a genus of annual, winter annual, or perennial flowering plants belonging to the family Caryophyllaceae. They are commonly called mouse-ears or mouse-ear chickweeds. There are 214 accepted species found nearly worldwide but with the greatest concentration in the northern temperate regions. 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: x2000 when printed at 10cm wide.