What are the rings in a woody stem made up of?

Monocots have bundles of xylem and phloem mixed throughout their stem with vascular cambium between, an arrangement found on many herbaceous plants. Dicots, like trees and many woody stems, organize their parts in rings. A cork cambium, the growth layer, is found between the xylem and phloem in the ring

Explanation:

The rings in a woody stem is made up of cork cambium.

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