Staghorn Sumac (Rhus typhina): A New Bioindicator to Detect Phytotoxic Levels of Ambient Ozone in the Eastern United States

In our air pollution studies at The Pennsylvania State University, we have successfully used Prunus serotina (Black Cherry), Asclepias syriaca (Common Milkweed), Apocynum androsaemifolium (Spreading Dogbane), and Ailanthus altissima (Tree-of-Heaven) as ozone-sensitive bioindicators to detect phytotoxic levels of ambient ozone. However, ambient ozone concentrations have decreased in our study area, and we are seeking a more sensitive bioindicator species. We observed significant levels of ambient ozone-induced leaf injury (stipple) on native Rhus typhina (Staghorn Sumac) within a field in a central Pennsylvania, suggesting that this species might serve as a new and highly sensitive ozone bioindicator. Therefore, we conducted a preliminary survey to determine the incidence and severity of ozone-induced stipple on Staghorn Sumac. In the same location, we concurrently evaluated the level of foliar stipple on the ozone-sensitive bioindicator species listed above. Staghorn Sumac developed significantly greater ozone-induced symptoms than the other bioindicators and has potential to serve as a bioindicator to detect phytotoxic levels of ambient ozone in the eastern US.