Slide 23: Cross section of a vascular bundle of a monocot. Surrounding the bundle is a sheath of sclerenchyma cells. Notice that the bundle looks rather like a face. The large cells (the "eyes") which are stained red, are xylem vessels. The green "forehead" is phloem. The larger cells in the phloem are the sieve elements; the smaller cells are the companion cells. The "nose" area is an airspace that is created when the first-formed xylem elements are stretched and destroyed as the stem elongates.