Rodríguez-Peña, Rosa A, and Andrea D. Wolfe. “Effect of Climate, Anther Morphology and Pollination Syndrome on Pollen Availability in Penstemon: Factors That Affect Pollen Availability in Penstemon”. Journal of Pollination Ecology 35 (December 15, 2023): 296–311. Accessed October 12, 2024. https://www.pollinationecology.org/index.php/jpe/article/view/703.