Anatomically fairly old dicotyledonous root is distinguished from the dicotyledonous stem by :
Anatomically fairly old dicotyledonous root is distinguished from the dicotyledonous stem by :
Position of protoxylem
absence of secondary xylem
Absence of secondary phloem
Presence of cortex
Solution
Explanation:
In dicotyledonous roots, the protoxylem is located toward the center (in the endodermis, in a star-shaped arrangement), while in dicotyledonous stems, the protoxylem is usually located toward the outside (in the vascular bundles).
Other options:
Absence of secondary xylem: Both stems and roots can have secondary xylem, but the arrangement is different.
Absence of secondary phloem: Secondary phloem is present in both stems and roots, particularly in older roots and stems.
Presence of cortex: Both stems and roots have cortex, but it is not a distinguishing feature between them.
Thus, position of protoxylem is the key distinguishing feature.