Effect of air pollution on the foliar morphology of some species in the family Euphorbiaceae in southwestern Nigeria

Abstract

Morphological studies of the leaves of ten species in the family Euphorbiaceae collected from three different locations with different pollution levels in Southwestern Nigeria were carried out in order to establish the effect of air pollution on these species. The study was carried out in both dry and wet seasons. Climatic data and pollutants concentration levels of the study sites were determined. Leaf area of all the species was measured using an established nondestructive method while petiole length was determined using metric ruler. The result showed that most species showed significant reductions (p<0.05) in the leaf area and petiole length across the three locations and this reduction is from rural to sub-urban to urban areas. Among all the species that showed reductions in leaf area, Alchornea cordifolia showed the highest response while Euphorbia hyssopifolia, E. hirta and Croton lobatus do not show clear reductions. Similar significant reductions were recorded for petiole length with the highest impact recorded in Manihot esculenta while species like E. hyssopifolia, E. hirta, C. lobatus and Flueggea virosa were not significantly reduced. This study showed that plants generally respond to air pollution with reduction in foliar morphology and the response is species specific.Keywords: Pollution, leaf morphology, Euphorbiaceae, leaf area, petiole length