Decoding Leaf Wettability: The Role of Physicochemical Leaf Traits in Hydrophytic Plants

Leaf wettability refers to the extent to which water adheres on leaf surfaces., which can have positive or negative effect on leaf, plant and ecosystem functioning. Hydrophytic plants have developed morphological adaptations to cope up with the excess presence of water. In this study, we analyzed contact angles and key physicochemical leaf traits including length, width, area, thickness, water adhesion, stomatal density, trichome density, surface structure, and surface free energy of nine wetland plant species belonging to three different habitats i.e. floating, submerged and emergent, on the basis of leaf position, from the Western Ghats of Maharashtra. Measurements were taken for both the adaxial and abaxial surfaces to determine the correlations between these traits and leaf wettability. Among the examined traits, surface free energy emerged as the primary determinant of hydrophobicity, exhibiting a strong negative correlation with contact angle. Contact angles ranged from 61° to 143° on the adaxial surface and from 47° to 124° on the abaxial surface. While most other physical traits did not show significant correlation, the presence of trichomes in Pistia stratiotes a floating hydrophyte enabled the formation of water beads on its surface. Additionally, Scanning Electron Microscopy (SEM) was employed to investigate the microstructural and nano-structural features of both sides of the leaf, providing further insights into their role in wettability. Studying the adaptations of the hydrophytes to their environment reveals that incorporating wettability and nano structural surface traits, along with other plant characteristics, enhances our understanding of plant–water interactions in wetland ecosystems.