Comparative wood anatomy of four vernonia delile species (Asteraceae) in southwestern Nigeria

Abstract

Wood anatomy of four Vernonia Delile species in Southwestern States of Nigeria was investigated with a view to identifying the  anatomical features of the genus that could be used to delimit the taxa. Plant samples were collected from Oyo, Ekiti, Osun and Ondo  States. Transverse, tangential and radial longitudinal sections were made from the wood of the species of Vernonia using Reichert sliding microtome at 10µm thickness. The woods were also macerated with Schultze's fluid to separate the tissues and cells. The macerates and  cut sections were stained with Safranine O reagent to reveal the differences in tissue arrangements, shapes and cell inclusions. The four  species showed common anatomical features: pore shape at transverse plane are oval, round, rectangular circular to cylindrical, simple  pitting of vessel elements and presence of - uniseriate, biseriate and multiseriate rays. The wood characteristics that can be used to  distinguish the taxa are absent and presence of : tylose, fibre length and percentage of solitary vessel, axial parenchyma type and its  absence. These features conferred significant taxonomic difference in the species and members were categorized into three major  groups. These findings serve as baseline for further research such as molecular studies.