Final answer:
Monocot stems have vascular bundles scattered throughout the ground tissue, whereas dicot stems (eudicots) have vascular bundles arranged in a distinct ring.
Step-by-step explanation:
Monocot stems have discrete regions of xylem and phloem arranged scattered throughout the ground tissue; herbaceous dicot stems have discrete regions of xylem and phloem arranged in a distinct ring. In monocots, the vascular bundles are randomly scattered within the stem, which is a defining characteristic of this group. On the other hand, dicots (or more specifically eudicots) typically have their vascular bundles organized in a circular pattern around the periphery of the stem's ground tissue, which forms the familiar ring seen in cross sections of their stems.