Why are xylem and phloem called complex tissues?

Complex tissues are

In leaves, xylem and phloem are present

When xylem and phloem are on same radius, the vascular bundles are said to be:-

Xylem and phloem are responsible for

Why parenchyma is called a simple tissue?

The term meristem, xylem and phloem were coined by

The type of vascular bundle in which xylem and phloem are situated at same redius, is called

Separate xylem and phloem bundles are know as

Secondary xylem and phloem in dicot stem are produced by

Secondary xylem and phloem in dicot stem are produced by