In each of vascular bundles in the dicot stem, xylem and phloem are on the same radius with xylem situated towards the pith and phloem situated towards the pericycle and a strip of cambium separates the two. This strip of cambium that separates the phloem and xylem is called interfascicular cambium. Therefore the only structure not present in the vascular bundle of a dicot stem is intrafascicular cambium. The correct answer is option C.