Anatomy Of Flowering Plants

In closed type of vascular bundle, no cambium is present between xylem and phloem.

The presence of vascular bundles in a ring is a normal feature of dicotyledonous stems. However in several members of various families of dicotyledons, the vascular bundles are found to be in scattered condition in stem, e.g., Peperomia (Piperaceae), Elatostema (Urticaceae), Thalictrum, Anemone (Ranunculaceae), Nymphaea (Nymphaeacea), Papaver (Papaveraceae), etc.