Fig. 7.5-5b. Transverse section of a vascular bundle of sedge (Scirpus). As in Fig. 7.5-5a, this vascular bundle has a large hole (at X) caused by a protoxylem vessel element being torn apart by the continued growth of surrounding cells. The large vessels (marked with V) did not mature until this region of internode had stopped elongating: because the surrounding cells are not expanding, they are not pulling on these dead vessel elements so there is no tendency for them to be torn apart that happens only to the very first, smallest protoxylem tracheary elements, and usually just in internodes that elongate a great deal.