Robberecht, R. and M.M. Caldwell. 1978. Leaf epidermal transmittance of ultraviolet radiation and its implications for plant sensitivity to ultraviolet-radiation induced injury. Oecologia 32:277-287.

Summary. Leaf epidermal transmittance of ultraviolet radiation (280-400 nm) was examined in several plant species to determine the capability of the epidermis to attenuate solar ultraviolet radiation. Epidermal samples were mechanically isolated and examined with a spectroradiometer/integrating sphere for transmittance. A survey of 25 species exposed to natural insulation was conducted. Although the species differed in life form, habitat type, and epidermal characteristics, epidermal transmittance was generally less than 10%. Ultraviolet radiation was attenuated 95 to 99% in more than half of the species. In 16 species, flavonoid and related pigments in the epidermis accounted for 20 to 57% of the attenuation. Several species exposed to supplemental ultraviolet irradiation (288-315 nm) in a greenhouse exhibited significant (P < 0.05) depressions in epidermal transmittance of 31 to 47%, apparently resulting from an increase in ultraviolet-absorbing pigments.

This research was funded by grants from the United States National Aeronautics and Space Administration, Department of Transportation, and the Environmental Protection Agency.