Another beautiful provision is seen in the difference in size of the
pollen-grain of the two flowers, those of the high anthers being much
larger than those from the lower anthers. These larger grains are
intended for the high stigma, which they are sure of reaching, while
those of smaller size, on the top of the tongue, which should happen
to be wiped off on the high stigma, are too small to be effective for
fertilization.