Stomatal sensitivity to air humidity : a hypothesis for its control through peristomatal evaporation

Analysis of previously published data shows that an extremely close correlation (r(2) = 0.83) exists between stomatal sensitivity to changes in leaf to air vapor pressure deficit and the maximum leaf conductance at low VPD in a wide range of plant species. The hypothesis is presented that stomatal sensitivity to changes in VPD is related to the evaporative area of the stomatal apparatus coupled with a large hydraulic resistance between the epidermal cells and the bulk of the leaf