<i>Ricinus communis</i> (IMAGE) Max-Planck-Gesellschaft Caption The flower of the castor oil plant Ricinus communis. Scientists have now unraveled the mysteries of the action mechanism of what is regarded as one of the oldest medicinal plants known to man. Credit Richard Drew / <a href="http://Dreamstime.com">Dreamstime.com</a> Usage Restrictions None 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.