Conclusions
We have demonstrated that stomata may constitute a major pathway for FWU when open. The measured water fluxes suggest that the main mechanism underlying the transport of water across stomata is vapor diffusion through the stomatal pore, with in-leaf distribution being a combination of diffusion and liquid paths (same as across the cuticle). Further, we propose that the interplay between cuticular conductance and the capacity of the stomata to remain open can be a specific trait that allows for opening stomata in response to surface hydration. The total amount of water absorbed by FWU cannot sustain transpiration, but it can provide a means of survival allowing for the recovery of plant physiological functions after severe stress. Future research on leaf surface dynamics, e.g. stomatal responses to water condensation and temperature or cuticular changes as affected by temperature or degree of hydration can contribute to better understand FWU mechanisms and functional significance.