Leaf trichomes (hairs) may have multiple key roles in leaf water relations, affecting transpiration rates and leaf water potential. Additionally, trichomes have been hypothesized to influence foliar surface water uptake, an extremely common phenomenon, contributing to rehydration from water deficits overnight. The hydraulic conductance of the epidermis to surface water uptake (KSWU = epidermal uptake/ water potential driving force) may depend on trichome properties as well as cuticle composition and potential uptake through closed stomatal pores, and may be adaptive in species adapted to arid conditions. Using fog chambers, and measuring foliar water uptake for hours, we tested for variation in KSWU across 12 species of native California woody species from a range of environments, including paired species with and without leaf trichomes within six genera. We also tested the relationship of KSWU with trichomes and other leaf structural and pressure-volume traits.
Results/Conclusions
Species varied substantially in KSWU for species with and without leaf hairs, within and across the genera. We explore the associations of KSWU with structural and water relations traits. These findings both further establish the generality of foliar water uptake, and its variation across diverse leaves in association with structure and adaptation.