Question

Secondary xylem and phloem in dicot stem are produced by

• A. phellogen
• B. vascular cambium
• C. apical meristems
• D. axillary meristem

Answer 1

The correct option is B vascular cambium

In dicot stems intrafascicular cambium derived from the procambium is present between primary xylem and primary phloem. The cells of medullary ray that adjoin the intrafascicular cambium become meristematic and form the interfascicular cambium. As a result, a continuous ring of cambium is formed. The cambial ring cuts off new cells, both towards the inner and the outer sides. The cells cut off towards pith, mature into secondary xylem and the cells cut off towards periphery mature into secondary phloem.

Phellogen or cork cambium gives rise to the cork (phellem) and secondary cortex (phelloderm).

Apical and axillary meristems are primary meristems.