Direct foliar effects of simulated acid rain. II. Leaf surface characteristics

Surface characteristics and wettability of the leaves of six plant species have been examined in relation to their susceptibility to damage from simulated acid rain. The species examined differed in the type and extent of epicuticular wax deposits, surface topography of the cuticle, trichome type and distribution, and epidermal cell shape. Leaf wettability, as measured by either water-holding capacity or droplet contact angle, was significantly different among species, and is highly correlated with previous reports of damage from simulated acid rain. The leaves of Platanus occidentalis L. were the most wettable of the species examined and are reported to be damaged the most by repeated applications of simulated acid rain. Mature leaves of Liriodendron tulipifera L., with high contact angles and very low water-holding capacity, are the least damaged according to published reports. Leaf water-holding capacity and surface-droplet contact angle may be useful first indicators of resistance to acid rain, and should be included in future studies of foliar effects of acid rain.