Taxonomic characteristics of xylem anatomy in some species of Euphorbia in Nigeria

This study uses xylem-based traits to examine the anatomical and ecological adaptations of four Euphorbia species (E. milii, E. hirta, E. heterophylla, and E. thymifolia). The research aims to investigate the xylem anatomy of these species to provide valuable taxonomic data for classification and identification. By analyzing and comparing the xylem characteristics, this study highlights the effects of xylem structure on the species’ adaptation and ecological strategies. Four species have been collected from the garden within the premises of the Department of Plant Biology, University of Ilorin and submitted after identification to the Herbarium. Thin transverse stem sections have been prepared using a manual microtome, then processed with graded isopropanol, embedded in paraffin wax, sectioned at 4 μm, stained with safranin, and observed under a light microscope. The results have revealed significant variations in vessel dimensions, fiber thickness, and parenchyma organization among the species. E. milii has exhibited large vessel lumens for rapid water conduction, while E. thymifolia hasshown smaller vessels and thinner fibers, suggesting adaptation to water-limited environments. Euphorbia heterophylla has demonstrated the largest pit diameters and abundant ray parenchyma supporting efficient water transfer. A principal component analysis (PCA) has revealed that Principal Component 1 (PC1) (53.82% variance) and Principal Component (PC2) (40.03% variance) feature the species variation, with E. milii and E. thymifolia separated by PC1, and E. heterophylla distinguished by PC2. These findings underscore the ecological significance of xylem adaptations in water transport, mechanical stability and environmental resilience, offering insights into the taxonomy and functional anatomy of the genus Euphorbia.