Q.3 Which one of the following is NOT a plant vascular tissue?
(A) Phloem
(B) Periderm
(C) Stele
(D) Xylem

Answer: (B) Periderm

Plant vascular tissues primarily consist of xylem and phloem, which conduct water, minerals, and nutrients, while periderm serves a protective role and is not part of this system.​

Option Analysis

Phloem transports sugars and organic nutrients bidirectionally from leaves to other plant parts via living sieve tube elements and companion cells. It qualifies as vascular tissue essential for plant nutrition.​

Periderm forms a secondary protective layer replacing the epidermis during growth, comprising phellem (cork), phellogen (cork cambium), and phelloderm, but lacks conduction functions. This is not a vascular tissue.​

Stele represents the central vascular cylinder in roots and stems, enclosing xylem, phloem, pericycle, and sometimes pith, defining the core vascular system.​

Xylem conducts water and minerals unidirectionally from roots upward through dead, lignified tracheids and vessels, providing structural support.​

Plant vascular tissue forms the lifeline of higher plants, enabling transport of water, minerals, and nutrients across roots, stems, and leaves. Key components like xylem and phloem define this system, but not all named tissues qualify—periderm stands out as the non-vascular option. This detailed guide breaks down “which one of the following is NOT a plant vascular tissue” for CSIR NET aspirants focusing on plant anatomy.​

Vascular Tissue Essentials

Vascular tissues xylem and phloem work together: xylem moves water upward via tracheary elements, while phloem distributes sugars bidirectionally. The stele encompasses these as the central cylinder, including pericycle and pith.​

Why Periderm is Excluded

Periderm develops from cork cambium during secondary growth, forming protective bark-like layers against stress, not conduction. Unlike vascular tissues, it blocks water loss and pathogens via suberized cells.​