Comparative anatomical studies of responses of some roadside plants to highway automobile exhausts

Abstract

Urena lobata and Hyptis suaveolens growing along busy roadsides in Lafia, Nigeria were carefully sampled. This was with a view to investigate the effect of continuous impact of automobile exhausts on internal structures of the plants. Three major highways were chosen for study in Lafia. Plant samples were systematically collected in replicates from 0 m, 10 m and 20 m away from defined points of the roadsides. Leaf and stem anatomical sections were prepared for microscopic examinations following established procedures. The plants were observed to have more stomata and smaller area of guard cells at 0 m than those away from the roadsides. For H. suaveolens, the thickness of epidermis, thickness of vascular bundles, length and number of trichomes at 0 m are higher than those at 10 m and 20 m. The reverse was observed for U. lobata. However, U. lobata showed high number of parenchyma cells closer to the roadsides than those father away. Consequently, H. suaveolens seemed to have ability to withstand and thrive well in areas of heavy air pollution. These anatomical changes were described to be distinct with regards to individual species and could have been as a result of cumulative effects of air pollutants.

Keywords: Air pollutants, Anatomy, Hyptis suaveolens, Lafia, Urena lobata