Air pollutants and epidermal traits in Ricinus communis L.

Eighty-five samples of leaves of Ricinus communis L. (Euphorbiaceae) representing five populations—four collected from healthy, and one from polluted, environments—were studied to establish the relationship between environmental pollution and foliar epidermal features. The data obtained were analysed statistically.

Stomatal frequency per square millimetre and the percentage of abnormal stomata (single guard cell or both the guard cells aborted) on both the upper and the lower epidermis showed a marked increase in plants growing ni polluted areas. One or two per cent of stomata on the lower epidermis also showed a slight decrease in size. A correlation between idioblast frequency and pollution was also observed.

Scanning electron microscopic studies of the foliar surface revealed that stomatal openings were larger and cuticular striations more conspicuous in leaves of polluted populations than in those of healthy ones.