Richard Crang


Emeritus Professor of Plant Biology
655 Morrill Hall MC-116
(217) 333-0616


Ph.D., 1965, University of Iowa


Multiple microscopic approaches have been used to determine the impact of various air pollutants on foliar structure of forest and agricultural plant species. Pollutants have included gaseous agents, acidic mists, and ultraviolet irradiation.


For example, hybrid poplar plants under conditions of SO2 fumigation typically show signs of degradation which microscopically are identical with senescence. Fumigation of Liriodendron tulipifera shoots with ozone results in leaf tissues with swollen mesophyll cells due to distended vacuolar structures, and their chloroplasts exhibit wavy, dissociated thylakoids. When NOx (primarily NO2) is a fumigant, chloroplasts possess greater stroma extensions, more developed thylakoid structure, but with less starch content. Thus, gaseous fumigants often exhibit their own distinctive patterns of impact microscopically.


When acidic misting regimes have been employed with L. tulipifera, developing leaves exposed to atmospheric pH values below 5.7 are diminished in size. Scanning electron microscopy of such leaves reveals changes in epicuticular wax morphology, becoming eroded and fused at lower pH levels.


Recent studies have also been directed at the impact of atmospheric deposition through semi-quantitative assays of cellular element content in Arctic species, e.g., mosses and lichens. These studies are also aimed at revealing the effectiveness of these plants as bioindicator species for air pollution studies. The work has considerable value in the application of microscopy to assess air pollution impacts on Arctic plants.


Quantitative methods for light and transmission electron microscopy have been developed and correlated with physiological and enzymatic data for experimental plants under environmental stress. An ultraviolet-sensitive cultivar of soybean has been studied which shows a significant decline in total peroxidase activity levels after exposure to UV-B radiation. A general reduction of foliar mesophyll air spaces, and an increase in polyphenolic inclusions has also been noted with light microscopy.


Ra HS, Geiser LH, Crang RF. (2005) Effects of season and low-level air pollution on physiology and element content of lichens from the U.S. Pacific Northwest. Sci Total Environ. 343:155-67.


Kinsel MJ, Briggs MB, Crang RF, Murnane RD. (2004) Ventricular phytobezoar impaction in three micronesian kingfishers (Halcyon cinnamomina cinnamomina). J Zoo Wildl Med. 35:525-9.


Ra HS, Rubin L, Crang RF. (2004) Structural impacts on thallus and algal cell components of two lichen species in response to low-level air pollution in pacific northwest forests. Microsc Microanal. 10:270-9.