Micromorphological and anatomical alterations caused by simulated acid rain in Restinga plants:: Eugenia uniflora and Clusia hilariana

Eugenia uniflora and Clusia hilariana seedlings were submitted to simulated acid rain, pH 3, for 40 days. The degree of visible injury and the anatomical and micromorphological alterations were determined 24 hours after the last simulation. E. uniflora presented a higher degree of leaf necrosis. The adaxial epidermis and part of the palisade parenchyma of the entire leaf blade were affected and hypertrophy, hyperplasia and cicatrization tissue differentiation occurred. Erosion and morphological modification of the epicuticular wax and alterations in the epidermis were detected on the upper and lower leaf surfaces. Stomata with deformed ostioles and rupture of the stomatal ledge were observed. C. hilariana presented necrosis in leaf margin and in abaxial leaf surface, showing collapsed cells or with plasmolized aspect, cicatrization tissue, epicuticular wax alterations, occasional leaf perforations, irregular arrangement of adaxial epidermis cells and twisted subsidiary cells. The structural alterations indicated a greater susceptibility of E. uniflora to acid rain. he lower sensibility of C. hilariana can be related with the anatomical characteristics as: thick cuticle with evident cuticular flanges, three layers of hypodermis and mesophyll more thick and compact.