Poplar Trees (IMAGE) University of Washington Caption The darker, taller poplar trees shown at the test site at the end of their third season were inoculated with microbes, while the shorter, lighter-green trees (center row) were not given the bacteria. Credit John Freeman/Intrinsyx Technologies Corporation 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.