The anomaly here, of course, is the bicollateral bundles. If your section was old enough to have begun secondary growth, you should note that vascular cambium activity occurs only between the xylem and external phloem. No additional internal phloem will be added via secondary growth. Also look at the lignified xylem parenchyma cells surrounding the vessels. These cells usually have wall protuberances and are transfer cells.
Transfer cells are common in xylem and especially phloem parenchyma, primarily at the nodes.
This is also a good time to examine the longitudinal section of Cucurbita stem for phloem features. While studying the phloem, be sure to check the lateral walls for sieve areas. The end walls or sieve plates are very obvious. Next observe the Lycopersicon older stem cross section for isolated phloem strands. These will sometimes occur in the pith While these strands are highly unusual in stem internodes, they are surprisingly common in nodal sections of many dicots.