Ragweed Observations (IMAGE) University of Washington Caption The study drew on more than 700 documented observations of common ragweed in the eastern US. Credit M. Case and K. Stinson/<i>PLOS ONE</i> Usage Restrictions With credit 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.