The developmental changes occurring in the vascular cambium ofDelonix regia have been studied in different age group trees having different circumferential central axis. It has been found that the cambial cells undergo considerable variation both in their number and dimension with the growing age. The fusiform initials experience a linear expansion by local apical growth, while the ray initials undergo rapid multiplication. The former loses ability of apical expansion and the latter continues to multiply and occupy more area of the cambial cylinder with increasing age.