What Is Bi Collateral Vascular Bundle?

What Is Bi Collateral Vascular Bundle? In a bicollateral bundle, the phloem is both outside and inside the xylem, as in Solanaceae (the potato family What is bi collateral? of a vascular bundle. : having the phloem both external and internal to the xylem — compare collateral. What is meant by bi collateral vascular bundle?