Development of Vascular Cambium and Compression Wood Formation in the Shoot of Young Spruce (Picea Jezoensis Var. Hondoensis)
In the course of the righting movement in young spruce trees (Picea jezoensis Carr. var. hondoensis Rehd.) inclined at 45°, the occurrence of compression wood associated with the development of vascular cambium in the shoot was observed. In shoots, the recovery first took place at the mid point, a few days after inclination. The observations of serial cross sections taken from the apex downward revealed no appreciable difference in the development of the procambium-cambium continuum between the upper- and underside of the shoot. The formation and structure of primary tracheary elements were similar, irrespective of the site of the procambium in the shoot. No compression wood cells occurred before the vascular cambium cylinder was complete. The stimulus of compression wood formation is received only by the differentiating secondary xylem tissues derived from the cambium cylinder.