
The spots on these leaves are damage caused by ozone exposure. Specimen courtesy of Dr. Gretchen Smith, Department of Natural Resource Conservation, University of Massachusetts. Photo by Siobhan Starrs © Smithsonian Institution
The spots on these leaves are damage caused by ozone exposure. Specimen courtesy of Dr. Gretchen Smith, Department of Natural Resource Conservation, University of Massachusetts. Photo by Siobhan Starrs © Smithsonian Institution