Bicollateral vascular bundles have phloem both on the outer and inner side of xylem. All the three lie on the same radius. Usually a strip of vascular cambium is present on both outer and inner sides of xylem. Bicollateral bundles occur in Cucurbitaceae (e.g., Cucurbita pepo, Luffa cylindrica etc.) and some members of families Solanaceae, Convolvulaceae, etc.