Changes in leaf morphological and anatomical characters of some plant species in response to gemstone mining in southwestern Nigeria

Abstract

The responses of seven selected plant species to gemstone mining activities were investigated based on data obtained from exo- and endo- morphology of the leaves with the aim of establishing the responses of the plant species to gemstone mining pollution and the underlining mechanism which could possibly explain such responses. Both qualitative and quantitative methods, using visual and microscopic assessment were adopted. Results of the foliar morphology showed that most of the plant species had significant increase (p<0.05) in the leaf area and petiole length in polluted sites compared to those from unpolluted site though with noted variations in others. The observed morphological responses are associated with corresponding significant increase (p<0.05) in stomata frequency, epidermal cell number, glandular and non-glandular trichome frequency and length, cuticle thickness, upper and lower epidermis. However, characters such as stomata size and palisade mesophyll tissue were significantly (p<0.05) reduced. We conclude based on the data obtained in this study that plants generally respond differently to pollution due to mining through either increase or reduction in some of their external (leaf area and petiole length) and internal features. These depict adaptive mechanisms employed by the plants in order to cope with polluted environments.

Keywords: Plant morphology, Plant anatomy, Mining pollution, Leaf area, Petiole