Write about the open and closed condition of vascular bundles

Write about the open and closed condition of vascular bundles.

Open vascular bundles The cambium is found to be present in between the xylem and phloem, in open vascular bundles, e.g., In sunflower.
Closed vascular bundles When the cambium is absent, the vascular bundle is called as a closed bundles, e.g., Maize.