Closed vascular bundles lack

Suberin is a ..........

The distinguishing feature of open vascular bundles is the presence of

The vessel elements of angiosperms differ from other elements of xylem in having

In what respect do the conducting elements of the $Xylem$ differ from each other?

$A$ vascular bundle in which a group of xylem and a group of phloem are on the same radius with xylem near the pith and phloem near the cortex and both are not separated by the cambium,is called: