Abstract:It is said that Pinus massoniana Lamb, which growing in the Kwangtung province is of two forms, i.e., one possessing more resin and the other with less resin. In the present paper, both the wood structure and the physico-mechanical properties of the two form timbers which were collected from the northern part of the province have been preliminarily studied. They are about thirty years old. According to the wood anatomical characteristics, these forms may be distinguished as follows: the first form comparing with the second form has wider ring-width, lower late-wood percentage, thinner tracheid-wall thickness and larger lumen-width, shorter tracheid-length, more rays and more radial resin ducts, less in numbers of tangential wall pits on late-wood tracheids, shallowly dentate ray tracheids, and more window-like pits per cross-field. Above all, the ring width and the tracheid length are the salient features. Among the physico-mechanical properties of the two forms of timbers, only both the strength in tension parallel to the grain and the shearing strength parallel to the grain have reliable differences. Moreover, the strength index, the strength/weight ratio and the height-growth rate are higher in the second form than which in the first one. In comparison with the race from other localities, the Masson pine timbers grown in the northern part of Kwangtung are the strongest in the main strength properties.