Abstract: The number size and morphology of resin canals in secondary xylem of three species of normal and dwarf pines, i. e. Pinus thunbergii, P. tabulaeformis and P. densiflora, were comparatively studied. It was found that the number of resin canals in dwarf pines was significantly greater than in normal pines, while the size of resin canals in dwarf pines was invariably smaller than in normal pines. In addition, the epithelial cells around the canals of dwarf pines extended laterally, which made the outline of resin canals aliform-like. These findings might indicate that the raviations of resin canals representing a special adaptation to the unfavourable growth conditions were also correlated with the trend of shortening and narrowing of dwarf pines.

Key words: Pine tree, Dwarf pine tree, Resin canal