Question

How does secondary growth occcur in roots of the monocot and dicot plants?

Answer 1

Secondary growth is seen in dicots. Most monocots and herbaceous plants undergo little or no secondary growth.

Cambium is a thin layer of actively dividing cells which are responsible for secondary growth of plants. Cambial cells are undifferentiated cells which have the ability to get differentiated into different types of cells. Two types of cambium present in plants are vascular cambium and cork cambium.

Secondary growth in monocots is not observed as cambium  is absent between xylem and phloem in a vascular bundle. But there are exceptional cases in monocots like Dracena which exhibit secondary growth.