Lolium perenne (IMAGE) Frontiers Caption Perennial perenne, whose pollen is an important cause of allergic rhinitis Credit A. Menzel and Y. Yuan, Technical University of Munich Usage Restrictions Credit artists 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.