Outside Bees (IMAGE) Penn State Caption We found that bumble bees preferentially visited plants with pollen that had high P:L ratios. Here, a bumble bee forages on Senna hebecarpa, the most preferred plant species used in the study. Credit Anthony Vaudo, Penn State Usage Restrictions non commercial use only 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.