Q.59 Given below are two statements:

Statement-I: The periderm is a protective tissue of secondary origin in angiosperms and gymnosperms.

Statement-II: Periderm is the special type of protective tissue that occurs in underground organs of some families.

In the light of the above statements, choose the correct answer
from the options given below:

(A) Both Statement-I and Statement-II are true
(B) Both Statement-I and Statement-II are false
(C) Statement-I is true but Statement-II are false
(D) Statement-I is false but Statement-II are true

Solution to Question 59: Analyzing Statements on Periderm

Let’s break down the two statements step by step, evaluate their accuracy based on plant anatomy (focusing on secondary growth in vascular plants), and then assess each option. This ensures a clear understanding of why the correct answer is what it is.

Statement-I: “The periderm is a protective tissue of secondary origin in angiosperms and gymnosperms.”

• Evaluation: This is true.
  Periderm forms during secondary growth as a replacement for the epidermis. It consists of phellem (cork), phellogen (cork cambium), and phelloderm. This occurs in both angiosperms (flowering plants) and gymnosperms (e.g., conifers) when stems and roots thicken. The cork cambium arises from secondary meristem, confirming its secondary origin. Example: In dicot stems like sunflower, periderm protects against water loss and pathogens after bark formation.

Statement-II: “Periderm is the special type of protective tissue that occurs in underground organs of some families.”

• Evaluation: This is false.
  Periderm is not restricted to underground organs (roots) or “some families”—it’s a general protective tissue in older stems and roots of most woody plants across many families in angiosperms and gymnosperms. Underground organs like roots do develop periderm (e.g., in carrot or oak roots), but it’s not “special” to them; stems form it too (e.g., tree bark). The phrasing implies exclusivity to underground parts, which is incorrect. True underground-specific protections include rhizodermis or exodermis in some monocots, not periderm.

Option Analysis

• (A) Both Statement-I and Statement-II are true: Incorrect. Statement-II is false, so this doesn’t hold.

• (B) Both Statement-I and Statement-II are false: Incorrect. Statement-I is true.

• (C) Statement-I is true but Statement-II is false: Correct. Matches our evaluation—periderm is secondary in both plant groups (I true), but not limited to underground organs (II false).

• (D) Statement-I is false but Statement-II is true: Incorrect. Statement-I is true, and II is false.

Final Answer: (C)

Introduction to Periderm Protective Tissue Secondary Origin Angiosperms Gymnosperms

In plant anatomy, the periderm protective tissue secondary origin angiosperms gymnosperms plays a crucial role during secondary growth. This article decodes its formation, functions, and common exam misconceptions—like whether it’s exclusive to underground organs—perfect for NEET, CSIR NET, or botany students preparing for questions on secondary plant body.

What is Periderm? Structure and Origin

Periderm arises from the cork cambium (phellogen), a lateral meristem of secondary origin. It replaces the epidermis in older stems and roots of woody plants.

• Components:

  • Phellem (cork): Dead, suberized cells for waterproofing.

  • Phellogen: Meristematic layer producing phellem outward and phelloderm inward.

  • Phelloderm: Living parenchyma for storage and support.

This structure forms in both angiosperms (e.g., oak, apple trees) and gymnosperms (e.g., pine), protecting against mechanical injury, pathogens, and desiccation. Unlike primary epidermis, periderm allows lenticels for gas exchange.

Periderm in Angiosperms vs. Gymnosperms: Secondary Growth Role

• Angiosperms: Common in dicots (e.g., periderm in potato tuber stems or beet roots). Monocots rarely form it due to limited secondary growth.

• Gymnosperms: Prominent in conifer bark, providing fire resistance via thick cork layers.

Key point: Periderm is not a “special” tissue for underground organs—it’s widespread in aerial stems too, debunking myths in MCQs.

Common Misconception: Periderm in Underground Organs

Some confuse periderm with root-specific tissues like exodermis (in monocots). However, periderm occurs in both stems and roots across families, not just “some families” underground. Example: Carrot (Daucus carota, Apiaceae family) shows periderm in roots, but birch trees (Betulaceae) have it in stems.

Exam-Style MCQ Solved: Periderm Statements Analysis

Question: Statement-I: Periderm is protective tissue of secondary origin in angiosperms and gymnosperms. Statement-II: Periderm occurs in underground organs of some families.
Answer: (C) Statement-I true, II false.
This tests precise recall—vital for competitive exams.

Functions and Significance

• Barriers to water loss and microbes.

• Enables secondary thickening for tree girth.

• Evolutionary adaptation in woody perennials.

Illustration: Imagine a young stem’s epidermis stretching and rupturing—phellogen activates, building a tough periderm “armor” like tree bark.

Conclusion for Students

Mastering periderm protective tissue secondary origin angiosperms gymnosperms clarifies secondary growth. Practice similar MCQs to ace exams!