Anatomy Of Flowering Plants Notes

Introduction

The study of the anatomy of flowering plants is crucial for understanding the internal structure and functional organization of these plants. This topic is a significant part of the NEET Botany syllabus and involves the study of various tissues and their arrangements within different plant organs such as roots, stems, and leaves. This document will break down these concepts into manageable sections to aid in your preparation.

Tissue Systems

Flowering plants have three main tissue systems: dermal, ground, and vascular. Each of these tissue systems has specific functions and structures.

Dermal Tissue System

The dermal tissue system forms the outer protective covering of the plant.

• Epidermis: The outermost layer of cells, usually one cell thick, that protects the plant from mechanical injury and water loss.
  • Cuticle: A waxy layer present on the epidermis of aerial parts, preventing water loss.
  • Stomata: Pores in the epidermis, mainly on leaves, that facilitate gas exchange.
  • Trichomes: Hair-like outgrowths of epidermal cells that can reduce water loss and provide protection against herbivores.

Ground Tissue System

This system includes all tissues that are neither dermal nor vascular.

• Parenchyma: Fundamental tissue composed of thin-walled living cells that function in photosynthesis, storage, and secretion.
• Collenchyma: Living cells with thickened walls that provide support while allowing flexibility.
• Sclerenchyma: Dead cells with thick, lignified walls that provide mechanical support. It includes fibers and sclereids.

Vascular Tissue System

This system is responsible for the transport of water, nutrients, and food throughout the plant.

• Xylem: Conducts water and minerals from roots to other parts of the plant.
  • Tracheids: Long, thin cells with tapered ends.
  • Vessels: Shorter, wider cells that form continuous tubes.
• Phloem: Transports organic nutrients, particularly sucrose, from leaves to other parts of the plant.
  • Sieve Tube Elements: Long, tubular cells with sieve plates at their ends.
  • Companion Cells: Assist the sieve tube elements in their function.

Anatomy of Root

The structure of roots can vary between monocots and dicots.

Dicot Root

• Epidermis: Outermost layer.
• Cortex: Composed mainly of parenchyma cells.
• Endodermis: Innermost layer of the cortex with a Casparian strip.
• Pericycle: Layer just inside the endodermis where lateral roots originate.
• Vascular Cylinder: Contains xylem and phloem arranged in a radial manner.

Monocot Root

• Similar to dicot root but with a few differences:
  • Pith: Present in the center, unlike in dicot roots.
  • Vascular Bundles: Arranged in a ring.

Anatomy of Stem

The stems of monocots and dicots also show distinct differences.

Dicot Stem

• Epidermis: Outermost protective layer.
• Cortex: Includes collenchyma, parenchyma, and endodermis.
• Pericycle: Present as a discontinuous layer.
• Vascular Bundles: Arranged in a ring with cambium present between xylem and phloem.
• Pith: Central region filled with parenchyma cells.

Monocot Stem

• Epidermis: Outermost layer.
• Ground Tissue: Not differentiated into cortex and pith.
• Vascular Bundles: Scattered throughout the ground tissue, each surrounded by a bundle sheath.

Anatomy of Leaf

Leaves are the primary sites of photosynthesis and show adaptations for this function.

Dicot Leaf

• Epidermis: Upper and lower epidermis with stomata mainly on the lower side.
• Mesophyll: Differentiated into palisade parenchyma (for photosynthesis) and spongy parenchyma (for gas exchange).
• Vascular Bundles: Reticulate venation with xylem on the upper side and phloem on the lower side.

Monocot Leaf

• Epidermis: Both upper and lower epidermis have stomata.
• Mesophyll: Not differentiated into palisade and spongy parenchyma.
• Vascular Bundles: Parallel venation with bundle sheaths around the vascular bundles.

Secondary Growth

Secondary growth occurs in dicots and gymnosperms, leading to an increase in girth.

• Vascular Cambium: Produces secondary xylem (wood) and secondary phloem.
• Cork Cambium: Produces cork cells that replace the epidermis.

Summary

Understanding the anatomy of flowering plants involves studying the structure and function of various tissues and their arrangement in different organs. This knowledge is fundamental for NEET Botany and helps in understanding the physiological processes in plants.

Diagrams

Caption: Diagram showing the anatomy of a dicot root.

Caption: Diagram showing the anatomy of a monocot stem.

By breaking down these concepts and using appropriate examples and diagrams, you can master the anatomy of flowering plants and excel in your NEET Botany exam.