No visible injury was shown on leaf surface of Gendarursa vulgaris after pollution by the industrial low concentration chlorine gas (below 0.11mg/m3) over a long period of time. However, on those leaves polluted by industrial chlorine gas of high concentration (above 1.68mg/m3) even for a short period of time, imjury symptoms were seen with the naked eye. Those symptoms of injury took the form of needle spots, water blisters, mottles and patches.Chlorine gas entered the leaves through atomata and at first c...