Red spruce seedlings (Picea rubens Sarg.) were exposed to charcoal-filtered air, at 0.07 ppm or 0.15 ppm ozone (O3), alone or in combination with pH 4.2 or pH 3.0 acidified rain, and examined with scanning electron microscopy (SEM) to determine if epistomatal wax fine structure was affected. Acidified rain in combination with 0.15 ppm O3 produced changes in wax tubule morphology. Changes were moderate at pH 4.2 and severe at pH 3.0. Needles collected from Whiteface Mountain, New York, displayed injured epistomatal wax structure similar to that observed on needles exposed in the laboratory to 0.15 ppm O3 plus pH 3.0 acidified rain.
Krause, C. R. and Cannon, W. N. Jr.
"Epistomatal Wax Injury to Red Spruce Needles (Picea rubens Sarg.) Grown in Elevated Levels of Ozone and Acidified Rain,"
Scanning Microscopy: Vol. 5
, Article 27.
Available at: https://digitalcommons.usu.edu/microscopy/vol5/iss4/27