1. Starch grains decreased progressively after cambial activity was resumed in early spring until they disappeared in all the stem tissues.

2. Wood is the product of cambial activity in trees, and the seasonal activity style of cambium directly influences wood biomass production, structures and properties.

3. In consistent with the periodicity of cambial activity, the variability of peroxidase isozyme activity as demonstrated by isozymography was most sign.

4. Increasing and decreasing of stored starch were closely related to the periodicity of cambial activity during the year.

5. Between primary xylem and primary phloem there are 2—3 layers of parenchymatous cells, regularly or irregularly arranged, but no cambial zone can be recognized.

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6. The variations of polysaccharide content and zymogram and activity of peroxidase, esterase and amylase isozyme were related to the periodicity of cambial activity.

7. Increasing and decreasing of stored starch are closely related to the periodicity of cambial activity.

8. POD was mainly distributed in the radial walls of the cambial cells and expanding xylem cell, especially at the corner of cell wall and cell wall close to the primary pit field.

9. As all cells expand to their mature size, the cambial cells are Pushed outward.

10. The variability of esterase isozyme activity in the vascular tissues was in consistent with the periodicity of cambial activity.

11. No significant differences in tangential and radial width of cambial fusiform cell, length of vessel element, ratio of fiber and ray tissue were found among different stages.