Katja Meyer and Tino Köster, Bielefeld University (image) Bielefeld University Share Print E-Mail Caption The researchers Katja Meyer und Dr. Tino Köster harvested leaves from a thale cress plant over a three-day period to determine the biorhythm. Credit Photo: Bielefeld University Usage Restrictions The image may only be used with appropriate caption or credit. Share Print E-Mail 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.