Anatomical Characterization of Vessels in Selected Nigerian Wood Species of Verbenaceae Family

Abstract

Nature of vessels in selected Nigerian trees of Verbenaceae family was investigated for variations and similarities in this study. Wood samples were collected from the stems of Tectona grandis, Gmelina arborea, Vitex cienkowskii, Vitex doniana, Gmelina leichhardtii and Avicennia nitida at Forestry Research Institute of Nigeria, Ibadan. Wood samples were cut into about 20 μm sections using a Ritchet sliding microtome machine. Measurements of wood vessels were performed on an Olympus light microscope (CH Series) at 80 × magnification, Pore tangential diameter (PTD) was measured in the direction perpendicular to the rays at the transverse section, while pore radial diameter (PRD) was measured in the direction parallel to the rays at the transverse section. Results showed that values of pore radial diameter (PRD) ranged from 53.6 µm in Avicennia nitida to 294 µm in Vitex doniana; pore tangential diameter (PTD) ranged from 53.6 µm in A. nitida to 245 µm in V. doniana; A. nitida had the least solitary pores of 5.27 % as most pores were in clusters, while T. grandis had the highest solitary pores of 73.78 %. Generally, PRD was higher than PTD among the wood species, this might be due to procumbent rays in which pores were sandwiched forcing vessels to assume an oval shape. All the wood species possessed pore pairs; and there were inclusions in vessels in form of either gum or tyloses. Whereas few differentiating characters include the number of solitary pores which were few in A. nitida and G. leichhardtii but high in T. grandis and V. doniana. These findings may enhance wood identification and utilization of the members of the family.