Comparative Anatomy of Leaf Epidermis in Five Species of Acacia in Zamfara State

Acacia species are ecologically and economically important trees across the Sudano-Sahelian zone of North West Nigeria, and comparative leaf anatomical data are important for taxonomic clarity and adaptational studies in Zamfara State where multiple species co-occur. This study compared the leaf epidermal anatomy of five Acacia species (Acacia senegal, Acacia nilotica, Acacia seyal, Acacia sieberiana, and Acacia tortilis) occurring in Zamfara State. Fresh mature leaflets were collected from five individual plants of each species, fixed in FAA, sectioned using a hand microtome, and stained with Safranin and Fast Green. Light microscopy was used for anatomical examination. Epidermal characters examined included stomatal type, stomatal density, stomatal index, guard cell length, epidermal cell shape, and presence of trichomes. Results showed that all five species possessed paracytic (Rubiaceous) stomata on the abaxial surface only. Stomatal density ranged from 112 to 248 per mm2, with A. nilotica having the highest density. Stomatal index varied from 14.2 (A. seyal) to 22.8 (A. senegal). Trichomes were present on both surfaces of A. sieberiana and A. nilotica but absent in A. senegal. Epidermal cell shape was polygonal in all species but differed in wall sinuosity. Multivariate discriminant analysis correctly classified 91% of specimens to species based on epidermal characters alone. The study demonstrates that leaf epidermal anatomy provides reliable taxonomic markers for Acacia species differentiation in Zamfara State.

Keywords: leaf anatomy, Acacia, stomatal characteristics, taxonomy, Zamfara State