The xylem and phloem strands alternate with each other separated by parenchymatous cells. Such kinds of vascular bundles are called radial and are found mainly in roots.
When the xylem and phloem of a vascular bundle lie on the same radius, it is called the conjoint vascular bundle and is found mainly in stems.
A vascular bundle in which one vascular tissue surrounds the other, so they appear to be arranged concentrically when viewed in the transverse section.
Bicollateral vascular bundles are those which have phloem on both sides of the xylem