Taxonomic significance of stem and petiole anatomy of three white varieties of Vigna unguiculata (L.) Walp.

Abstract

Anatomical studies were carried out on the stem and petiole of three white varieties of Vigna unguiculata L. (Walp.) belonging to the family Fabaceae consumed in Awka Anambra State Nigeria. The structures of the stem and the petiole showed the basic structure of a dicotyledonous plant. The transverse section of the stem and petiole consists of epidermal and collenchyma layers, parenchyma cells and stele (vascular bundles, secretory cells and pith); however there were differ-ences in shape and position of the vascular bundles. In the stem, this bundles are located on a continuous ring but in the petiole are cutting and divided into two large adaxial and three abaxial bundles forming main foliar trace, which above it lie laterally a pair of secondary bundles. The relationships found in this study provide insights to the phylogeny of the species and revealed the importance of combined data from different taxonomic evidences to have clearer information on varietal relationships to enhance the delimitation of Vigna species.