Ragweed Pollen Grains (IMAGE) Johns Hopkins University Caption This microscopic image shot by the research team shows individual pollen grains, including some that haven't fully divided or matured. Credit Mike Martin/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.