Ragweed Study (IMAGE) Johns Hopkins University Caption Johns Hopkins environmental engineering graduate students Mike Martin, left, and Marcelo Chamecki, at the 18-acre ragweed field where they are studying how the allergy-provoking plant grows, reproduces and scatters its irritating pollen. Credit Will Kirk/JHU 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.