Comparative Foliar Epidermal Micromorphology of Four Medicinal Plant Species from Rivers State University Campus, Port Harcourt, Nigeria

Abstract

This study investigated the foliar epidermal micromorphology of four medicinal plant species (Ocimum gratissimum, Mentha piperita, Aspilia africana, and Vernonia amygdalina) collected from the Rivers State University campus in Port Harcourt, Nigeria. Fresh leaf samples were processed using standard epidermal peeling techniques, stained with safranin and methyl blue, and examined under a compound light microscope. Quantitative parameters including trichome density and dimensions, epidermal cell characteristics, and stomatal features were measured and analyzed using ANOVA. Results revealed considerable interspecific and surface-specific variation in epidermal traits. Aspilia africana exhibited the highest abaxial trichome density (9.33 ± 1.53 trichomes per field) and stomatal density (40.33 ± 6.03 stomata per field), while Menthapiperita displayed the largest guard cells on the abaxial surface (71.19 ± 10.20 µm). Ocimum gratissimum showed the highest adaxial epidermal cell density (92.00 ± 31.19 cells per field) and the longest adaxial trichomes (138.93 ± 88.79 µm). Significant differences (p < 0.05) were observed among species for several parameters including abaxial trichome width, abaxial epidermal cell number, adaxial epidermal cell length, adaxial epidermal cell width, abaxial stomatal number, abaxial guard cell length and width, adaxial stomatal pore length, and adaxial stomatal pore width. These micromorphological variations reflect adaptive strategies and provide taxonomic evidence useful for species identification and authentication.