On the systematic implication of foliar epidermal micro-morphological and venational characters: diversities in some selected Nigerian species of Combretaceae

Abstract

Foliar epidermal micro-morphology and venation patterns of eleven species representing four genera in the family Combretaceae revealed stable foliar anatomical characters that are diagnostic and are important in separating the taxa. Distinguishing characters of taxonomic significance in the cells and tissues structures of the species include epidermal cell shape, stomata type, stomata frequency, stomata index, trichome micro-morphology and frequency, areolation shape, vein micromorphology as well as distribution of druses within areoles. Numerous epidermal striations on the abaxial surface of lamina are diagnostic for Combretum zenkeri while C. platypterum is distinctly separated from other taxa by the possession of staurocytic stomata in addition to the prominent anomocytic and/or anisocytic stomata. The simple unicellular non-glandular trichomes in the genus Combretum indicate a generic attribute classificatory for members of the genus. Druses within the areoles classify C. platypterum, Terminalia catappa, T. superba and Quisqualis indica within and across the genera studied. This study which is in line with most previous studies revealed that characters of epidermal micromorphology and venation patterns are important in the identification and separation of the taxa discussed, and that the placement of the species in each of their respective genus should be maintained.