Secondary Growth in Dicot Stem

Schematic diagram of primary and secondary growth in dicot stem 
Image source: https://commons.m.wikimedia.org/wiki/File:Crescita_primaria_e_secondaria_del_fusto.png#file

Figure 1. Secondary growth in dicot stem: a. & b. promeristem; c. young stem; d. formation of cambium ring; e. secondary growth in the first year; f. secondary growth in third year.

Figure 2. L. S. of Cambium ring showing fusiform and ray initials

Figure 3. T. S. of a part of two years old dicot stem showing secondary growth

Figure 4. T. S. of trunk showing sapwood and heartwood

Figure 5. Secondary growth due to activity of cork cambium