Differences in cuticular ozone flux to Quercus ilex leaves treated with various compounds (see panel labels) and abscisic acid to induce stomatal closure in the laboratory. Cuticular ozone fluxes are a function of relative humidity (RH). Error bars represent the random error calculated according to Sun, S., Moravek, von der Heyden, et al. (2016). Figure is adapted from Figure 6 of Sun, S., Moravek, Trebs, et al. (2016) with permission. © 2016. American Geophysical Union. All Rights Reserved.