Ryegrass (IMAGE) American Society of Agronomy Caption Crossing block of annual ryegrass cycle 3 of selection for germination at 40 degrees C. Credit Courtesy of Eric Billman Usage Restrictions For use with this story only. 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.