Poplar tree cuttings in a tissue culture (IMAGE) University of Toronto Caption Researchers looked at the role waxes play in poplar trees for the study. Credit Don Campbell Usage Restrictions Editorial use only. No sales or archives. License Original 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.