Ecological Differentiation and Adaptive Significance of Foliar Epidermal Traits in Duranta erecta L. Across Nigerian Ecological Zones

The foliar epidermis serves as a critical interface between plants and their environment, reflecting both taxonomic identity and adaptive responses to ecological pressures. This study examined the qualitative and quantitative foliar epidermal characteristics of 38 accessions of Duranta erecta L. collected from diverse ecological zones across Nigeria. Micromorphological analyses revealed a conserved hypostomatic condition but substantial variation in stomatal types (anisocytic, anomocytic, brachyparacytic, and paracytic) as well as in trichome structure and distribution. Both glandular and non-glandular trichomes were consistently present, underscoring their functional relevance in stress tolerance and defense. Undulating anticlinal cell walls, particularly pronounced in variegated accessions, indicated structural modifications associated with mechanical stability and light stress mitigation. Quantitative parameters exhibited distinct ecological structuring: accessions from savannah zones displayed higher stomatal density and index but smaller stomatal size, whereas those from rainforest zones had larger but fewer stomata. Principal Component Analysis revealed clear clustering patterns corresponding to ecological origin, confirming the influence of local adaptation on epidermal morphology. The results emphasize the combined effects of phylogenetic constraint and phenotypic plasticity in shaping epidermal features of D. erecta, highlighting their diagnostic and adaptive significance in ecological and taxonomic contexts.