Leaf blade structure and the tolerance of Acer negundo L. (Box elder) to the polluted environment

Polluted air is a stress factor that contributes to the decline of urban trees. Air pollution may causeshort-term (acute) damage, which is immediately visible, and long-term (chronic) damage, which can lead togradual tree decline. Long-term damage may predispose trees to other disorders. The impact of technogenicfactors on the leaf’s anatomical structure of Acer negundo L. (Box elder) was studied. The thickness of the upper cuticle is increased when compared to those from an ecologically pure area. A change in the rate ofmesophyll tissue is due to the enlargement of the palisade parenchyma. The thickness of lower epidermal cellsis decreased. All changes in the leaf blade structure are significant and are in the direction of increasing the xerophyte characteristics of the leaves. Box elder is native to much of temperate North America. This is a tree of lowlands and wet hardwood forests. As such, we can assume that the registered changes are adaptive responses of the tree to the contaminated environment and that the tree can be considered to be relatively tolerant.