The occurrence of resin canals in branches of Cedrus deodara with different inclination angles

Resin canals play an important role in gymnosperm taxonomy, and the initiation of the resin canals in branches of C. deodara remains controversial. Therefore, the common wood anatomical method was used to investigate the existence of resin canals in the C. deodara branch with different inclining angles (45°, 90° and 135°), and the regularity of its occurrence is summarized by describing its radial and axial distribution pattern. It shows that the ratio of occurrence of resin canals (RORC) gradually decreases from pith to phloem in the branch base. Meanwhile, RORC is increasing generally from the base of the branch to the tip. Furthermore, the main distributing area of resin canals existed at the third or fourth growth ring at beginning, and it moved towards the bark until it arrived at around the twentieth growth ring along with the axial position moving from the tip of the branch to the base. Besides that, it was found that branches with an inclining angle of 45° have more resin canals than other angles, and it also happens to compression zones when compared to other peripheral positions. Variance analysis showed that both inclining angle and peripheral position had significant effect on the RORC.