Stomata Development (IMAGE) University of Washington Caption The gene Speechless drives the division that initiates stomatal development. (Without Speechless, cells become the wax-coated, interlocking pavement cells on the surface of the plant, none of which open or close.) Two or three divisions after Speechless, Mute causes the formation of a guard mother cell. Then Fama causes the guard mother cell to divide into two equal guard cells that, as their name implies, guard the opening of the stomatal pore. Credit University of Washington Usage Restrictions Graphic credit required License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.