The Role of Leaf Wettability and Morphology on Leaf Surface Water Storage: A Cross‐Biome Synthesis

ABSTRACT The presence of water on leaves impacts plant function and ecosystem fluxes by supplementing moisture, reducing evapotranspirational demand and encouraging pathogen spread. Maximum phytoelement water storage capacity (MWSC)—the maximum amount of water that can be held on the surface of the leaf‐ is an important but poorly constrained parameter that influences the effect of leaf wetting. Most studies on this parameter study one ecosystem and disagree on the measurement methodology. Here, both spraying and submergence techniques are used to measure MWSC of nine plant species from ecosystems selected across an aridity gradient. Our results show that spraying consistently yields higher MWSC, though the two methods were strongly and positively correlated (). Hydrophobic leaves generally hold more water, and more hydrophobic leaves exhibit a greater difference between values derived from spraying and submergence. The presence of trichomes increased both hydrophobicity and spray‐based holding capacity and decreased submergence‐based holding capacity. Additional leaf surface structures like finely serrated leaf margins, while not captured by the contact angle measurement, enhanced spray‐based holding capacity. Plant species from arid biomes have higher MWSC, while plant species from other biomes did not exhibit a significant difference in MWSC. Further investigation is needed to disentangle the effects of leaf orientation and time of sampling on these results. Data synthesis also highlights the need for standardized methodologies and data from dry sub‐humid and arid ecosystems in future research to better compare results across different biomes.