Variations in Anatomical Characteristics of 21-Year-Old Polyalthia longifolia (Sonn) in Ibadan 1 Ogunsanwo, O.Y., 1 Umar Mohammed and 2 Adedeji, G. A 1. Department of Forest Resources Management, University of Ibadan, Ibadan, Nigeria 2. Department of Forestry and Wildlife Management, University of Port Harcourt, Port Harcourt, Nigeria Ogunsanwo, O.Y., Umar Mohammed and Adedeji, G.A. (2014): Variations in anatomical characteristics of 21-year-old Polyalthia longifolia (Soon) in Ibadan. Nigerian Journal of Forestry, 44(1&2): 76-83 Abstract The study assessed variations in anatomical properties of 21-year-old Polyalthia longifolia obtained in Ibadan Oyo state, Nigeria with the view to exploring its utilisation potentials as utility pole and for other product. Wood samples were systematically collected from the inner, middle and outer wood of the radial position to investigate fibre characteristics namely; fibre length, fibre diameter, lumen width and wall thickness as well as the cell proportions were determined along the radial position of the tree stem. The mean fibre length of Polyalthia longifolia along the radial position is 1.18mm, fibre diameter is 9.38μm, lumen width is 5.92μm and wall thickness is 1.88μm. Except fibre length, no significant difference was observed in the fibre characteristics along the radial position at (p< 0.05). The cell proportion was in this order; 11.28%, 55.70%, 22.16% and 10.85% for vessels, fibre, ray and axial parenchyma respectively. It was concluded from this study that the fibre characteristics and cell proportion studied showed an increasing trend with the increase in cambial growth. The results of the anatomical properties studied are comparable with other prominent hardwood species and Polyalthia longifolia wood could serve as a suitable substitute. Key word: lesser used species, radial variation, fibre length, wall thickness, cell proportion, Introduction Wood is a complex structure, been the product of trees with individual characteristics especially in hardwood species where the wood is compost of different cellular structures such fibres, vessels, rays and parenchyma cells (Zhang and Zhong 1992). Understanding the variation in anatomical properties wood of this species in terms of size, distribution and dimension is important in tree breeding and wood utilisation, since variations in physiological functions of a standing tree and other wood properties such as strength is mainly the function of differential expression of anatomical properties and hence affecting the end use quality (Zobel and van Buijtenen 1989). Vessels play an active role in the to and fro conduction of water and sap between the roots and the crown while fibres are chiefly responsible for the strength and longitudinal shrinkage of the wood (Panshin and de Zeeuw, 1980). Cell diameter in relation to cell wall thickness and the proportion of thin walled to thick walled cells determine density which is closely correlated to mechanical strength, machining and working properties and yield in pulping (Ocloo and Laing, 2003; Hamid et al., 2011). Polyalthia longifolia commonly called mast tree, masquerade or police tree as it is popularly called in Nigeria. It is a single-stemmed lofty evergreen tree originally from India, belonging to the family Annonaceae and it is mostly distributed in places like tropical Africa, South and Southeast Asia (Mitra, 1993). The tree can grow up to a height of 15-20 meters tall and exhibits symmetrical pyramidal growth with willowy weeping pendulous branches and long narrow lanceolate leaves with undulate margins. Flowers are non fragrant pale green, non-fragrant and about 2.5-3.5 cm in cross section. The fruits are green in colour but turns purple or black when ripe. Seeds are pale brown, ovoid, with a longitudinal groove (Lemmens, 2003). Polyalthia longifolia is one of the plants known to have curative values believed to have strong medicinal influence particularly in its place of origin. Various pharmacological investigations have shown that Polyalthia longifolia possess significant biological and pharmacological activities such as antibacterial, antifungal, antitumor, anti-ulcer, antidiabetic and antioxidant properties (Jothy et al., 2013). It is successfully grown in Nigeria where it is mainly used for its aesthetic value as ornamental tree. The tree has assumed a continually increasing role in landscaping system. This high rate utilisation is probably due to its fast growth, straight bole formation, suitable root system, and resistance to wind thrown. The wood has been reported to be tough, flexible and moderately hard Nigerian Journal of Forestry Vol. 44 Nos 1 & 2 (www.njf-ng.org) 76