Question

The difference between the arrangement of vascular bundle of a stem and root is that stem is

• A. Endarch
• B. Exarch
• C. Mesarch
• D. Polyarch

Answer 1

The correct option is A Endarch

Endarch is the arrangement in which the protoxylem is directed towards the center and metaxylem elements towards the periphery. The development of the xylems in this arrangement follows the centrifugal pattern. It is the characteristics of the stem of flowering plants. Whereas, exarch is the arrangement in which the protoxylem is directed towards the periphery and metaxylem towards the center. The development of the xylem in this arrangement follows the centripetal pattern. It is the characteristics of roots.
Mesarch is used when there is more than one strand of primary xylem in a stem or root and the xylem develops from the middle of a strand in both directions. The metaxylem is thus, on both the peripheral and central sides of the strand with the protoxylem between the metaxylem. The leaves and stems of many ferns have mesarch development. Polyarch is the characteristic of monocot roots.
Thus, the correct answer is option A.