Anatomy of flowring plants class 11th

Anatomy of a Flowering Plant refers to the internal structure of the various parts of a flowering plant — including roots, stems, leaves, and tissues. It helps in understanding how these parts function and support plant growth and development.

When we talk about the Anatomy of Flowering Plants, we specifically mean the internal structure and organization of:

Roots
Stems

Leaves

Flowers

Seeds

Why Study Plant Anatomy?

1. Understanding Internal Structure: Helps identify how tissues and cells are arranged.

2. Function Insight: Explains how water, minerals, and food move within a plant.

3. Agricultural Use: Essential for improving crop yield and resistance.

4. Environmental Adaptations: Shows how plants adapt structurally to different habitats.

1. Meristematic Tissues

Meristematic tissues are a type of plant tissue made up of undifferentiated, actively dividing cells. These tissues are responsible for the growth of plants, both in length and thickness.

These tissues are found in specific regions of the plant, like the tips of roots and shoots, and play a crucial role in forming new cells for development.

Types of Meristematic Tissues

Meristematic tissues are classified based on position in the plant body:

1. Apical Meristem

2. Intercalary Meristem

3. Lateral Meristem

1. Apical Meristem

Apical meristem is a type of meristematic tissue found at the tips of roots and shoots. It is responsible for the primary growth of the plant, meaning it increases the length of the plant body.

Location:

At the tips of roots and shoots. Growing points of young leaves and flowers.

Function:

Brings about primary growth – increase in plant length. Produces primary tissues like the protoderm, ground meristem, and procambium which give rise to epidermis, cortex, and vascular tissue respectively.

Example: Shoot apex, root apex.

2. Intercalary Meristem

Intercalary meristem is a type of meristematic tissue found between mature tissues, especially at the base of leaves or internodes (the region between two nodes). It is responsible for regrowth and elongation in certain parts of the plant.

Location:

Base of leaves or internodes (common in grasses).

Function:

Helps in elongation of internodes. Aids in regrowth of parts after injury or cutting (e.g., grass blades). Supports rapid vertical growth in plants like bamboo and sugarcane.

Example: Found in sugarcane, bamboo, grasses.

3. Lateral Meristem

Lateral meristem is a type of meristematic tissue found along the sides of stems and roots. It is responsible for the secondary growth of plants, meaning it increases the girth (thickness) of roots and stems.

Location:

Present along the lateral sides of stems and roots. Found in dicotyledonous plants and gymnosperms.

Function:

Causes increase in diameter of stem and root (secondary growth). Produces wood (secondary xylem) and secondary phloem. Forms protective outer tissue like cork. Helps form annual rings in woody trees (used to determine age).

Example: Found in vascular cambium and cork cambium (phellogen).

Types of Lateral Meristem:

Type Function

Vascular CambiumForms secondary xylem & phloem
Cork CambiumForms protective cork and secondary cortex

NEET Tip: Focus on the location and function of each meristem type. Diagrams and match-the-following type MCQs are commonly asked.

2. Permanent Tissues –

Permanent tissues are plant tissues made up of mature cells that have lost the ability to divide. These tissues arise from meristematic tissues after they undergo differentiation (specialization in structure and function).

They are responsible for performing specific, permanent functions in the plant such as support, conduction, and storage.

Permanent tissues are of two main types:

1. Simple Perment Tissues

2. Complex perment Tissues

1. Simple Permanent Tissues –

Simple permanent tissues are made up of only one type of similar cells, which perform common and specific functions. These tissues are non-dividing and fully matured, and their main roles include support, storage, and photosynthesis.

They are part of the ground tissue system in plants.

Types of Simple Permanent Tissues:

1. Parenchyma

2. Collenchyma

3. Sclerenchyma

1. Parenchyma

Parenchyma is the most basic and abundant type of simple permanent tissue in plants. It consists of living cells with thin cell walls and large central vacuoles. Parenchyma plays a vital role in storage, photosynthesis, and tissue repair.

Functions of Parenchyma:

Storage of food, water, and nutrients (e.g., in roots, fruits).
Photosynthesis (when chloroplasts are present → called Chlorenchyma).
Buoyancy in aquatic plants (large air cavities → called Aerenchyma).
Wound healing and tissue repair in injured plants.

Location in Plant Body:

Cortex and pith of stems and roots

Leaf mesophyll (in case of chlorenchyma)

Flesh of fruits and seed coats

Types of Parenchyma (Based on Function)

Parenchyma is a versatile and living simple permanent tissue that modifies itself to perform different functions like photosynthesis, storage, buoyancy, and healing. Based on these functions, parenchyma is classified into the following types:

Chlorenchyma
Aerenchyma
Storage Parenchyma

Chlorenchyma –

Chlorenchyma is a modified form of parenchyma that contains chloroplasts, the green pigment-containing organelles. It plays a vital role in photosynthesis, making it one of the most important tissues in green parts of plants.

Functions:

Performs photosynthesis — prepares food using sunlight.
Helps in gaseous exchange due to intercellular spaces.
May contribute to temporary storage of starch produced during photosynthesis.

Location:

Found in the mesophyll layer of leaves (especially in palisade and spongy parenchyma).

Present in young green stems, sepals, and fruits.

Chlorenchyma = Parenchyma + Chloroplasts → Main photosynthetic tissue in leaves.

It's commonly found in dicot leaves, in both palisade (upper layer) and spongy (lower layer) regions.

Aerenchyma –

Aerenchyma is a specialized type of parenchyma tissue with large air-filled spaces between cells. It is commonly found in aquatic plants (hydrophytes) and plays a crucial role in providing buoyancy and facilitating gaseous exchange.

Functions:

Provides buoyancy – helps aquatic plants float.
Facilitates gaseous exchange – ensures oxygen reaches submerged parts.
Helps in internal air circulation within plant parts.

Location:

Found in submerged stems and roots of aquatic plants like:

Lotus
Water hyacinth
Hydrilla
Pistia

Storage Parenchyma –

Storage parenchyma is a form of parenchyma tissue that functions primarily in storing food, water, and other substances. It is made up of living, thin-walled cells and is commonly found in roots, stems, seeds, fruits, and tubers.

Functions:

Stores starch, proteins, oils, and other nutrients.
Acts as a water reservoir in succulent plants.
Provides energy during germination and growth.

Location in Plant Body:

Roots – e.g., carrot, beetroot
Tubers – e.g., potato (starch storage)
Seeds – e.g., castor (oil storage), pulses (protein storage)
Fruits and stems – e.g., banana, cactus (water storage)

Remember examples of storage parenchyma based on stored material:

Starch → Potato
Oil → Castor seed
Water → Cactus
Protein → Pulses

2. Collenchyma –

Collenchyma is a type of simple permanent tissue made up of living cells with unevenly thickened cell walls. It provides flexibility and mechanical support to young, growing parts of the plant.

Location in Plants:

Found just below the epidermis in dicot stems, petioles, and midribs of leaves.
Absent in monocot stems.

Functions of Collenchyma:

Provides mechanical support to young parts of the plant.
Allows flexibility — helps plants bend without breaking.
Can perform photosynthesis if chloroplasts are present (in some cases).

3. Sclerenchyma –

Sclerenchyma is a type of simple permanent tissue made up of dead cells with thick, lignified secondary walls. It provides mechanical strength and rigidity to mature plant parts.

Location in Plants:

Found in hard parts like:
Seed coats (e.g., pea, castor)
Nut shells
Husk of coconut
Fibres in stems and leaves
Vascular tissues (xylem fibres)

Functions of Sclerenchyma:

Provides mechanical support and rigidity to the plant.
Protects inner tissues in hard structures like seeds and shells.
Helps in conducting water (when present in xylem as fibres).

Remember the difference:

Parenchyma: Living, soft, storage

Collenchyma: Living, flexible, support in young parts

Sclerenchyma: Dead, rigid, support in mature parts

2. Complex Permanent Tissues –

Complex permanent tissues are plant tissues made up of more than one type of cell that work together as a unit to perform a common function, mainly related to transport of water, minerals, and food.

Unlike simple tissues (which are made of similar cells), complex tissues consist of different kinds of cells, both living and dead.

Types of Complex Tissues:

Xylem
Phloem

1. Xylem –

Xylem is a complex permanent tissue in plants responsible for the conduction of water and minerals from roots to all parts of the plant. It also provides mechanical support due to the presence of thick-walled cells.

Location in Plant:

Found in roots, stems, and leaves as part of vascular bundles.
Especially well developed in woody dicots.

Direction of Transport:

Unidirectional – water moves from roots → to leaves only.

2. Phloem –

Phloem is a complex permanent tissue in vascular plants responsible for the transport of food (mainly sucrose) from leaves to other parts of the plant. This transport is known as translocation.

Location in Plant:

Found in vascular bundles of stems, roots, and leaves, along with xylem.

Direction of Transport:

Bidirectional – depending on the source and sink.

Example: From leaves to roots in summer, roots to shoots in spring.

Tissue System –

The tissue system in plants refers to the grouping of tissues based on their location, structure, and function. In a plant body, individual tissues do not work in isolation — instead, they function as part of broader tissue systems that work together to support growth, protection, and transport.

A tissue system is an organizational unit in plants where different tissues are grouped and arranged in a specific pattern to perform common functions. These systems arise from meristematic tissues during development.

1. Epidermal Tissue System

2. Ground Tissue system

3. Vascular Tissue System

1. Epidermal Tissue System –

The epidermal tissue system is the outermost protective covering of the plant body. It forms a continuous layer of closely packed cells that covers the leaves, young stems, roots, flowers, and fruits.

Key Features:

Made up mostly of living, flat, and tightly packed cells.
Generally single-layered and without intercellular spaces.
Cells are usually parenchymatous and have no chloroplasts (except guard cells).
Outer walls of epidermal cells are often thickened and covered with a waxy cuticle to prevent water loss.

Functions of Epidermal Tissue:

Protection – guards internal tissues from injury, water loss, and infection.
Prevents excessive transpiration – via cuticle.
Allows gaseous exchange – through stomata.
Absorption of water – via root hairs.
Secretion – in some plants, epidermis produces wax, oils, or mucilage.

Location:

Leaves → protective layer + stomata
Stems → protective outer layer (with cuticle)
Roots → root hairs aid in absorption

2. Ground Tissue system

The ground tissue system forms the main bulk of a plant's body. It includes all tissues except the epidermal and vascular tissues, and it plays a vital role in photosynthesis, storage, support, and regeneration.

Characteristics:

Found in all parts of the plant: roots, stems, and leaves.
Derived from fundamental meristem.
Composed of parenchyma, collenchyma, and sclerenchyma tissues.
May vary in structure and function depending on organ type (leaf, root, stem).

Organization by Plant Part:

In roots: Ground tissue is mostly parenchyma, used for storage.
In stems: Forms cortex, pith, and hypodermis; supports structure.
In leaves: Forms the mesophyll, where photosynthesis occurs (includes palisade and spongy parenchyma).

Functions of Ground Tissue:

Photosynthesis (in leaves)
Storage of food and water
Support and strength
Healing and regeneration (in damaged tissues)

3. Vascular Tissue System –

The vascular tissue system is responsible for the transport of water, minerals, and food throughout the plant. It consists of two complex permanent tissues: xylem and phloem.