Leaf and Petiole Micro-Anatomical Diversities in Some Selected Nigerian Species of Combretum Loefl.: the Significance in Species Identification at Vegetative State

Leaf and petiole samples of four Combretum Loefl. species which were identified in the Herbarium (IFE) were investigated anatomically in search of stable taxonomic micro-anatomical attributes to improve our knowledge of identification of members of the genus. Anatomical characters; in particular, upper and lower cuticles and epidermal structures, fibre structures, vascular architectures, petiolar outlines and trichome micro-morphology are good taxonomic tools to identify the taxa. The invariable uniseriate to multiseriate upper and lower epidermis; the absence of trichome in the petiole and the presence of branched trichome in the mid-rib region of C. zenkeri P. Beauv delimit the taxa. Variations in vascular architectures can be used to identify the taxa while some other anatomical features in the genus suggest great taxonomic affinities. However, the artificial key, which was constructed using stable taxonomic characters, is a reliable taxonomic tool for proper identification of the four species and which can as well be employed in separating each of the taxa from their close relatives. A detailed micro-anatomical study of leaf and petiole structures of the Nigerian Combretum species may provide an invaluable tool for determination and identification of the four taxa studied, thereby assisting in promoting quality assurance in the genus.