Variation in Leaf Surface Hydrophobicity of Wetland Plants: the Role of Plant Traits in Water Retention

Leaf surface wetness has numerous physiological and ecological consequences, and the morphological structures on the leaf surface can affect its extent and duration, contributing to interception rates in the scale of the whole ecosystem. Wetland plants have developed morphological adaptations to high water level allowing them to avoid water excess. Droplet contact angle and surface free energy are measurable parameters which relate to how the plant influences water usage and redistribution. We analysed patterns of contact angle and the surface free energy of the adaxial and abaxial surface of 10 wetland plant species and related them to the optimal habitat conditions and functional traits of the plants. Despite the consistent environment of these plants, we found them to vary greatly in terms of leaf surface wettability and surface free energy, with contact angles ranging from 75 to 169A degrees and surface free energy, from 1.32 to 30.38 mJ/m(2). Canopy height and leaf longevity were significantly correlated to leaf wettability, whilst SLA (Specific Leaf Area) and leaf shape were not related to hydrophobicity. Investigating adaptations of wetland plants to their environment showed that including wettability and surface free energy in combination with other plant traits improves our understanding of water plant-soil-water interactions in wetland habitats.