Fig. 8.1-7a. Transverse section of root of catclaw (Smilax). In the roots of many monocots, the cells that make up the matrix (called conjunctive tissue) between the tracheary elements and the sieve tube members are thick-walled fibers. In comparison to their darkly stained, red walls, the thin-walled, green sieve tube members and companion cells (arrows) are easy to identify. Even at this low magnification, we know immediately where all the phloem is. Notice that it alternates with the masses of tracheary elements, near the outer edge of the xylem, and just a little interior to the endodermis. Learning the location here where it is easy to see will help you find the phloem in those monocot roots that have a parenchymatous conjunctive tissue.
See Fig. 8.1-7b for a higher magnification view.