A Study of Morphological, Physiological, and Anatomical Changes of Black Locust Tree (Robiniapseudoacacia L.) Affected by Air Pollution in Tehran

Air pollution is one of the most important environmental concerns in the developed and developing cities.The trees in the urban environments can improve the quality of the air. At the same time, these trees may be at risk of air pollution. Although Locust (Robiniapseudoacacia L.) is among the resistant trees which are compatible with a variety of climatic conditions, nowadays were are witnessing the early yellowing of parts of the leaves in these trees in Tehran. In an attempt to identify the attributes that results in plant resistance and its potential vulnerability aspects, some morphological, physiological, and anatomical features of Locust tree leaves were examined during late spring in three areas of Tehran:Sadra Park as the clean area, AlmahdiPark as the polluted zone No.1, and Avesta Park as the polluted zone No. 2. The results indicated that the stomatal transpiration, stomatal resistance, relative temperature of the leaves, and their relative humidity were significant at P