Morphological and Anatomical Characterisation of Parkia biglobosa (Locust Bean) Across Ecological Zones in Borno State

Parkia biglobosa (African locust bean) is a culturally and nutritionally significant tree across North East Nigeria, yet morphological and anatomical variation across ecological gradients in Borno State has not been systematically studied. This study characterised morphological and leaf anatomical traits of Parkia biglobosa across three ecological zones in Borno State: the Sudan savanna (Maiduguri), the dry sub-humid zone (Gwoza), and the semi-arid zone (Monguno). Leaf, pod, and seed morphological measurements were taken from 10 trees per ecological zone. Leaf anatomical sections were prepared from the mid-lamina using hand sectioning and observed under light microscopy. Morphological characters including leaflet length, leaflet width, pod length, pod width, seed diameter, and number of seeds per pod were measured and subjected to ANOVA and principal component analysis. Results showed significant differences in pod length (p < 0.01) and seed diameter (p < 0.05) across zones, with trees from the dry sub-humid Gwoza zone producing the longest pods (28.4 cm) and largest seeds. Leaf anatomical features including mesophyll thickness, epidermis thickness, and stomatal density also differed significantly across zones. Trees from the drier Monguno zone had significantly thicker cuticles and higher stomatal densities. Principal component analysis separated the three zones distinctly on a biplot, confirming ecotypic differentiation. The study concludes that Parkia biglobosa exhibits ecotypic variation in Borno State and recommends zone-specific accession selection for improved domestication and agroforestry programmes. Keywords: Parkia biglobosa, morphological characterisation, leaf anatomy, ecotypic variation, Borno State