Acknowledgments
We would like to thank Alexandra Kois and Kyle Krellwitz for assistance in the field and in pollen identification, along with Austin Staudinger, Erica Smith, Gabby Stamas, Cecilia Grinis, Oscar Li, and Drake Propson for assistance with pollen identification. We would also like to thank Dr. Murray Clayton for valuable assistance with statistical analyses. This work was supported by funds from the Garden Club of America – Centennial Pollinator Fellowship (2016) to DM, and funds from USDA-ARS to JB. The authors have no conflicts of interest to declare.