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.