Introduction

Anatomy of flowering plants, also known as Angiosperms, involves studying their internal structure. This topic covers the tissue organization, structure of different plant parts, and their functions.



Plant Tissues:

Plant tissues are classified into two main types:

1. Meristematic Tissues: These are actively dividing cells found in specific regions of the plant.

  Apical Meristem: Located at the tips of roots and shoots; responsible for primary growth.

  Intercalary Meristem: Present at the base of leaves or internodes; helps in the growth of grasses.

  Lateral Meristem: Found along the sides of stems and roots; responsible for secondary growth (increase in girth).

2. Permanent Tissues: These are derived from meristematic tissues and have lost the ability to divide.

Simple Permanent Tissues: Consist of similar types of cells.

Parenchyma: Basic packing tissue with thin cell walls.

Collenchyma: Provides support with irregularly thickened cell walls.

Sclerenchyma: Consists of dead cells with thick walls, providing mechanical strength.

Complex Permanent Tissues: Made up of different types of cells.

Xylem: Conducts water and minerals from roots to other parts of the plant. Components include tracheids, vessels, xylem parenchyma, and xylem fibers.

Phloem: Transports food from leaves to other parts of the plant. Components include sieve tubes, companion cells, phloem parenchyma, and phloem fibers.

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Structure of a Dicotyledonous Plant

1. Root:

Epidermis: Outermost layer; absorbs water and minerals.

Cortex: Contains parenchyma cells.

Endodermis: Innermost layer of the cortex with Casparian strips.

Pericycle: Gives rise to lateral roots.

Vascular Bundle: Contains xylem and phloem.

2. Stem:

Epidermis: Protective outer layer.

Cortex: Multi-layered with collenchyma and parenchyma.

Endodermis: Contains starch grains.

Pericycle: Layer between endodermis and vascular bundles.

Vascular Bundles: Arranged in a ring; xylem inside and phloem outside.

Pith: Central part with parenchyma cells.

3. Leaf:

Epidermis: Outer layer with cuticle and stomata.

Mesophyll: Middle layer with palisade and spongy parenchyma.

Vascular Bundles: Embedded within the mesophyll; consist of xylem and phloem.

Secondary Growth

Secondary growth results in an increase in the girth of stems and roots, primarily due to the activity of the vascular cambium and cork cambium (phellogen).

Vascular Cambium: Produces secondary xylem (wood) and secondary phloem.

Cork Cambium: Produces cork (outer bark) and secondary cortex (phelloderm).

MCQs on Anatomy of Flowering Plants

1. Which tissue is responsible for the growth in length of the plant?

  - a) Apical Meristem

  - b) Lateral Meristem

  - c) Intercalary Meristem

  - d) Permanent Tissue

  Answer: a) Apical Meristem

2. What is the function of sclerenchyma?

  - a) Photosynthesis

  - b) Storage

  - c) Support and mechanical strength

  - d) Transport of water

Answer: c) Support and mechanical strength

3. In which part of the plant would you find the Casparian strip?

  - a) Cortex

  - b) Endodermis

  - c) Pericycle

  - d) Epidermis

Answer: b) Endodermis

Summary

Understanding the anatomy of flowering plants involves studying their internal structure and organization of tissues. This knowledge helps in understanding the functional aspects and adaptations of plants.