A bicollateral vascular bundle is characterised by

Explanation

In the vascular bundles of this category, the phloem is found in two groups, one outside the xylem elements and the other inner to them. These are characteristically found in the stems of members of the family Cucurbitaceae. Due to the presence of the cambium, these are always open as in pumpkin (Cucurbita pepo) and ridge-gourd (Luffa cylindrica)