Anatomical Studies of the Foliar Epidermis and Petiole of some Lannea Species in Jos, Plateau State, Nigeria

Abstract

Aims: Leaf epidermal morphology and petiole anatomy of seven Lannea species namely; Lannea velutina, Lannea kerstingii, Lannea egregia, Lannea schimperii, Lannea acida, Lannea microcarpa, and Lannea edulis in Nigeria were investigated to provide new taxonomic characters that could help in proper identification and delimitation of the taxa. Place and Duration of Study: The study was carried out in the Department of Plant Science and Biotechnology, University of Jos, Nigeria between August 2020 and March 2021. Methodology: Transverse sections of petioles were cut using a rotary microtome and epidermal peels were made. Staining was done using Safranin and slides observed using a light microscope. Results: Stomatal distribution was hypostomatic except for L. velutina and L. edulis with amphistomatic distribution. Three stomata types are found; paracytic occurring in L. velutina, L. edulis and L. egregia, cyclocytic in L. schimperii and L. microcarpa and anomocytic in L. kerstingii and L. acida. Stomata index vary among taxa with L. egregia and L. acida having the highest (22.43%) and lowest (12.17%) respectively. The epidermal cell shape was polygonal in all the species and anticlinal wall patterns were straight to slightly curved. Unicellular/multicellular uniseriate trichomes were observed in L. schimperii, L. egregia and L. kerstingii distinguishing them from other species. Petiole outlines were circular to oval, epidermis was uniseriate and vascular bundles are collateral. Presence of continuous sclerenchyma rings surrounding the vascular bundles in L. kerstingii and L. microcarpa serve as a distinguishing character. Other distinguishing characters are presence of crystals, druses and phenolic idioblasts. A taxonomic key was produced using the anatomical character as an aid to the identification of the species. Conclusion: Variations observed in the stomata types, petiole outline, petiole vasculature type, trichome type and stomata index could be employed for species identification and delimitation.