Leaf surface influence on potential water use in desert plants

Water use in plants is complex with varied strategies, depending on species type and environmental conditions. The leaf surface wettability determines the spread of water droplets, with implications for water use. We examined the degree of leaf wettability and its persistence, by measuring the dynamic contact angle, base diameter, and volume of water droplets placed on the surface of three desert plant species, Artemisia sieberi, Salsola inermis, and Haloxylon scoparium. Leaf roughness was highly correlated to the amount of wax that was detected; the highest level was on S. inermis, which was 50% rougher than H. scoparium and A. sieberi. In addition, the water droplet contact angles on the A. sieberi leaf surface were more dynamic than on the other two species, starting at a high degree and then markedly decreasing, along with decreases in the volume and the base diameter; this implies absorption of the water drop, possibly due to the trichomes on the leaves. Droplets on both S. inermis and H. scoparium had a stable base diameter and showed only a slight decrease in volume, indicating no absorption. The various leaf surface characteristics determined the spread of water droplets on the leaf, presenting implications for leaf water absorption.