The document discusses secondary growth in dicot stems. It describes how the lateral meristem leads to increases in girth and thickness and the formation of vascular cambium. The cambium gives rise to secondary tissues including secondary xylem on the inner side, secondary phloem on the outer side, and secondary medullary rays passing through. Annual rings are formed from early wood in spring and late wood in autumn. Over time, sapwood converts to heartwood and a periderm forms with cork cambium, cork, and phelloderm.