Abstract
The six Shorea species native to Sri Lanka Beraliya dun (S. disticha), Navada dun (S. stipularis), Dun (S. zeylanica), Yakahalu dun (S. trapezifolia), Yakal dun (S. astylosa), and Thiniya dun (S. congestiflora) are commercially valuable timbers within the Dipterocarpaceae family, yet their close morphological resemblance creates substantial difficulties in accurate species-level identification across field, trade, and processing contexts. This study aimed to establish reliable wood anatomical criteria for distinguishing these six Shorea species through microstructural analysis and its quantitative relationship with timber density. Permanent sections in transverse, radial, and tangential planes were prepared and examined under light microscopy, with vessel diameter and ray dimensions measured using Micrometrics SE Premium imaging software, while timber density was determined through the water displacement principle. All six species exhibited solitary and multiple vessel arrangements, with mean vessel diameters differing considerably across taxa, providing a primary basis for microscopic discrimination. Ray structure ranged from uniseriate to multiseriate configurations, with measurable variation in ray height and width offering additional diagnostic value. Axial parenchyma patterns including paratracheal and apotracheal forms differed consistently among species, reinforcing anatomical boundaries at the cellular level. A statistically significant negative correlation was identified between wood density and vessel diameter, indicating that species with greater density characteristically develop narrower conducting elements. By integrating vessel arrangement, ray morphology, parenchyma distribution, and density values, a dichotomous identification key was constructed that successfully and unambiguously separates all six taxa. The anatomical framework and dichotomous key developed in this study offer timber inspectors, foresters, and wood processing industries a scientifically grounded, practical tool for the accurate identification of Sri Lankan dun timbers in both raw and processed forms