(also resin duct), in plants, a long canal filled with oleoresin. Resin canals develop as a result of the divergence of cells and the formation of large intercellular spaces. They are usually surrounded by a facing of parenchymatous cells or sclerenchymatous fibers. Resin canals are characteristic of the leaves and primary bark of young stems of all conifers. The xylem of pine has vertical and horizontal canals, whereas the phloem has only horizontal ones.