Question
Biology Question on Anatomy of Flowering Plants
What is the fate of primary xylem in a dicot root showing extensive secondary growth?
A
It is retained in the centre of the axis
B
It gets crushed
C
May or may not get crushed
D
It gets surrounded by primary phloem
Answer
It is retained in the centre of the axis
Explanation
Solution
The cambial ring becomes active and begins to cut off new cells, both towards the inner and outer sides. The cells cut off towards pith, mature into secondary xylem and the cells cut off towards periphery mature into secondary phloem. The primary and secondary phloems get gradually crushed due to the continued formation and accumulation of secondary xylem. The primary xylem however remains more or less intact, in or around the centre.