Shoot cross sections C3 versus C4 (IMAGE) Salk Institute Caption Cross sections of C3 rice (left) and C4 sorghum (right) shoots. Both grain crops evolved from a common ancestor, but sorghum evolved to photosynthesize more efficiently. Credit Tina Schreier at the University of Cambridge Usage Restrictions With credit and related coverage License Original 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.