Response of the vascular cambium to reorientation in patch grafts

Abstract

The vascular cambium was reoriented in square 5-mm panels of bark at 90° and 180° from the normal position in three varieties of Malus baccata and Malus sylvestris (ornamental crabapple), Cornus stolonifera, Sorbus aucuparia, and Thuja occidentalis, Douglasii pyramidalis. Panels grafted in the normal orientation served as controls. The cambium in the panels continued to function normally, and where it was reoriented, it retained the imposed orientation. The secondary vascular tissues that were produced likewise retained the imposed orientation, a feature which was particularly striking in the case of transversely oriented panels. In early growth after the grafting, the secondary xylem showed some histological abnormalities particularly in abnormally oriented panels, but these diminished in later-formed xylem in the case of normally and transversely oriented panels. It is concluded that the cambial initials possess a high degree of autonomy which is reflected in their resistance to realignment which would correspond to the lines of flow of nutrients and water in an axis into which they are grafted.