What part of the plant would show the following:
$(a)$ Radial vascular bundle
$(b)$ Polyarch xylem
$(c)$ Well developed pith

(MONOCOT ROOT) Radial vascular bundle: In roots,xylem and phloem are arranged in an alternating manner on different radii. This arrangement is known as a radial vascular bundle.
$(b)$ Polyarch xylem: When more than six groups of xylem are present,the condition is called polyarch. This is a characteristic feature of monocot roots.
$(c)$ Well developed pith: $A$ large,well-developed pith consisting of parenchymatous cells with intercellular spaces is a characteristic feature of monocot roots.