Anatomy of Flowering Plants: A Detailed Guide l NEET Notes

Introduction

The internal structure and organization of flowering plants provide insight into their growth, adaptation, and survival mechanisms. The anatomy of flowering plants involves the study of tissues and their arrangement in various plant organs. This topic is crucial for understanding plant physiology, taxonomy, and evolutionary relationships.

The plant body consists of three tissue systems:

1. Epidermal Tissue System

2. Ground Tissue System

3. Vascular Tissue System

Each system plays a vital role in the functioning, transport, and protection of the plant.

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1. The Tissue System

1.1 Epidermal Tissue System

• The epidermis forms the outermost protective layer of the plant.

• It consists of epidermal cells, stomata, and epidermal appendages like trichomes and root hairs.

• Cuticle: A waxy layer on leaves and stems that prevents water loss.

• Stomata: Small pores that regulate transpiration and gas exchange.

• Guard Cells: Bean-shaped cells controlling the opening and closing of stomata.

• Trichomes: Hair-like structures on the stem that reduce water loss and offer protection.

• Root Hairs: Increase the surface area for water and nutrient absorption.

1.2 Ground Tissue System

• Includes parenchyma, collenchyma, and sclerenchyma.

• Functions in photosynthesis, storage, and mechanical support.

• Parenchyma: Thin-walled cells, found in leaves (mesophyll) and pith.

• Collenchyma: Provides flexibility and support, found in young stems.

• Sclerenchyma: Dead, thick-walled cells providing strength (e.g., fibers and sclereids).

1.3 Vascular Tissue System

• Composed of xylem and phloem, forming vascular bundles.

• Xylem: Conducts water and minerals from roots to other parts.

• Phloem: Transports food (sugars) from leaves to different plant parts.

• Types of vascular bundles:

  • Radial: Xylem and phloem are arranged alternately (in roots).

  • Conjoint: Xylem and phloem are located on the same radius (in stems and leaves).

  • Open: Contains cambium (in dicots, allows secondary growth).

  • Closed: No cambium (in monocots, no secondary growth).

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2. Anatomy of Dicotyledonous and Monocotyledonous Plants

2.1 Dicot Root vs. Monocot Root

• Dicot Root:

  • Outermost layer: Epiblema with unicellular root hairs.

  • Cortex: Parenchyma with intercellular spaces.

  • Endodermis: Innermost layer of the cortex with Casparian strips (water-impermeable suberin deposits).

  • Vascular Bundles: Fewer xylem and phloem patches (2-4).

  • Cambium forms secondary xylem and phloem, leading to secondary growth.

• Monocot Root:

  • Similar structure but has more than six xylem bundles (polyarch condition).

  • Large, well-developed pith.

  • No secondary growth.

2.2 Dicot Stem vs. Monocot Stem

• Dicot Stem:

  • Epidermis with a cuticle and trichomes.

  • Cortex: Divided into hypodermis (collenchyma), middle parenchymatous region, and endodermis (starch sheath).

  • Pericycle: Present above phloem as sclerenchymatous patches.

  • Vascular Bundles: Arranged in a ring, open and conjoint (allows secondary growth).

  • Pith: Large, parenchymatous cells with intercellular spaces.

• Monocot Stem:

  • Scattered vascular bundles, each enclosed by sclerenchymatous bundle sheath.

  • Vascular Bundles: Closed and conjoint.

  • No vascular cambium; hence, no secondary growth.

  • Parenchymatous ground tissue (no clear cortex or pith differentiation).

2.3 Dicot Leaf (Dorsiventral) vs. Monocot Leaf (Isobilateral)

• Dicot Leaf (Dorsiventral Leaf):

  • Upper epidermis with cuticle (fewer stomata).

  • Mesophyll differentiated into palisade (elongated) and spongy parenchyma (loosely arranged).

  • Vascular bundles in reticulate venation (veins of varying thickness).

  • Lower epidermis with more stomata.

• Monocot Leaf (Isobilateral Leaf):

  • Stomata present on both epidermal layers.

  • Mesophyll undifferentiated (no separate palisade and spongy parenchyma).

  • Parallel venation (veins of nearly equal thickness).

  • Bulliform cells (help in leaf rolling under water stress).

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FAQs on Anatomy of Flowering Plants

1. What is the importance of studying plant anatomy?

Studying plant anatomy helps understand plant structure, adaptation, function, and evolutionary significance. It is also essential for taxonomy, pharmacology, and biotechnology.

2. How does the anatomy of monocots differ from dicots?

• Monocots have scattered vascular bundles, parallel venation, and no secondary growth.

• Dicots have vascular bundles arranged in a ring, reticulate venation, and undergo secondary growth.

3. What are the major functions of xylem and phloem?

• Xylem transports water and minerals from roots to the entire plant.

• Phloem distributes sugars and nutrients from leaves to various plant organs.

4. What are the different types of vascular bundles?

• Radial: Xylem and phloem alternate (roots).

• Conjoint: Xylem and phloem together (stems and leaves).

• Open: Cambium present (dicots, secondary growth possible).

• Closed: No cambium (monocots, no secondary growth).

5. Why do dicots undergo secondary growth, but monocots do not?

Dicots have vascular cambium, which helps in forming secondary xylem and phloem, leading to thicker stems. Monocots lack cambium, preventing secondary growth.

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Conclusion

Understanding the anatomy of flowering plants is crucial for studying plant physiology, adaptation, and evolutionary trends. The differences in root, stem, and leaf structure between monocots and dicots provide insights into their growth patterns, water conduction, and mechanical support. This knowledge is fundamental for botany, agriculture, and biotechnology research.

Also Read:

Morphology of Flowering plants Class 11 Biology NEET 2025