Grass Stomata (IMAGE) Carnegie Institution for Science Caption A comparison of the dumbbell-shaped stomata found in grasses and the kidney-shaped stomata found in many other plants. The shape of grass stomata is considered one of the reasons for their evolutionary success. Images are courtesy of Michael Raissig and Dominique Bergman. Credit Michael Raissig and Dominique Bergman. Usage Restrictions With credit 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.