ANATOMY OF FLOWERING PLANTS 71
C HAPTER 6
ANATOMY OF FLOWERING PLANTS
6.1 The Tissue You can very easily see the structural similarities and variations in the
System external morphology of the larger living organism, both plants and
animals. Similarly, if we were to study the internal structure, one also
6.2 Anatomy of
finds several similarities as well as differences. This chapter introduces
Dicotyledonous
you to the internal structure and functional organisation of higher plants.
and
Study of internal structure of plants is called anatomy. Plants have cells
Monocotyledonous as the basic unit, cells are organised into tissues and in turn the tissues
Plants are organised into organs. Different organs in a plant show differences in
their internal structure. Within angiosperms, the monocots and dicots
are also seen to be anatomically different. Internal structures also show
adaptations to diverse environments.
6.1 THE TISSUE SYSTEM
We were discussing types of tissues based on the types of cells present.
Let us now consider how tissues vary depending on their location in the
plant body. Their structure and function would also be dependent on
location. On the basis of their structure and location, there are three types
of tissue systems. These are the epidermal tissue system, the ground or
fundamental tissue system and the vascular or conducting tissue system.
6.1.1 Epidermal Tissue System
The epidermal tissue system forms the outer-most covering of the whole
plant body and comprises epidermal cells, stomata and the epidermal
appendages – the trichomes and hairs. The epidermis is the outermost
layer of the primary plant body. It is made up of elongated, compactly
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arranged cells, which form a continuous layer. Epidermis is usually single-
layered. Epidermal cells are parenchymatous with a small amount of
cytoplasm lining the cell wall and a large vacuole. The outside of the
epidermis is often covered with a waxy thick layer called the cuticle which
prevents the loss of water. Cuticle is absent in roots. Stomata are structures
present in the epidermis of leaves. Stomata regulate the process of
transpiration and gaseous exchange. Each stoma is composed of two bean-
shaped cells known as guard cells which enclose stomatal pore. In
grasses, the guard cells are dumb-bell shaped. The outer walls of guard
cells (away from the stomatal pore) are thin and the inner walls (towards
the stomatal pore) are highly thickened. The guard cells possess chloroplasts
and regulate the opening and closing of stomata. Sometimes, a few epidermal
cells, in the vicinity of the guard cells become specialised in their shape and
size and are known as subsidiary cells. The stomatal aperture, guard
cells and the surrounding subsidiary cells are together called stomatal
apparatus (Figure 6.1).
Epidermal cells
Subsidiary cells
Chloroplast
Guard cells
Stomatal
pore
Figure 6.1 Diagrammatic representation: (a) stomata with bean-shaped guard cells
(b) stomata with dumb-bell shaped guard cell
The cells of epidermis bear a number of hairs. The root hairs are
unicellular elongations of the epidermal cells and help absorb water and
minerals from the soil. On the stem the epidermal hairs are called
trichomes. The trichomes in the shoot system are usually multicellular.
They may be branched or unbranched and soft or stiff. They may even
be secretory. The trichomes help in preventing water loss due to
transpiration.
6.1.2 The Ground Tissue System
All tissues except epidermis and vascular bundles constitute the ground
tissue. It consists of simple tissues such as parenchyma, collenchyma
and sclerenchyma. Parenchymatous cells are usually present in cortex,
pericycle, pith and medullary rays, in the primary stems and roots. In
leaves, the ground tissue consists of thin-walled chloroplast containing
cells and is called mesophyll.
Reprint 2025-26
C HAPTER 6
ANATOMY OF FLOWERING PLANTS
6.1 The Tissue You can very easily see the structural similarities and variations in the
System external morphology of the larger living organism, both plants and
animals. Similarly, if we were to study the internal structure, one also
6.2 Anatomy of
finds several similarities as well as differences. This chapter introduces
Dicotyledonous
you to the internal structure and functional organisation of higher plants.
and
Study of internal structure of plants is called anatomy. Plants have cells
Monocotyledonous as the basic unit, cells are organised into tissues and in turn the tissues
Plants are organised into organs. Different organs in a plant show differences in
their internal structure. Within angiosperms, the monocots and dicots
are also seen to be anatomically different. Internal structures also show
adaptations to diverse environments.
6.1 THE TISSUE SYSTEM
We were discussing types of tissues based on the types of cells present.
Let us now consider how tissues vary depending on their location in the
plant body. Their structure and function would also be dependent on
location. On the basis of their structure and location, there are three types
of tissue systems. These are the epidermal tissue system, the ground or
fundamental tissue system and the vascular or conducting tissue system.
6.1.1 Epidermal Tissue System
The epidermal tissue system forms the outer-most covering of the whole
plant body and comprises epidermal cells, stomata and the epidermal
appendages – the trichomes and hairs. The epidermis is the outermost
layer of the primary plant body. It is made up of elongated, compactly
Reprint 2025-26
, 72 BIOLOGY
arranged cells, which form a continuous layer. Epidermis is usually single-
layered. Epidermal cells are parenchymatous with a small amount of
cytoplasm lining the cell wall and a large vacuole. The outside of the
epidermis is often covered with a waxy thick layer called the cuticle which
prevents the loss of water. Cuticle is absent in roots. Stomata are structures
present in the epidermis of leaves. Stomata regulate the process of
transpiration and gaseous exchange. Each stoma is composed of two bean-
shaped cells known as guard cells which enclose stomatal pore. In
grasses, the guard cells are dumb-bell shaped. The outer walls of guard
cells (away from the stomatal pore) are thin and the inner walls (towards
the stomatal pore) are highly thickened. The guard cells possess chloroplasts
and regulate the opening and closing of stomata. Sometimes, a few epidermal
cells, in the vicinity of the guard cells become specialised in their shape and
size and are known as subsidiary cells. The stomatal aperture, guard
cells and the surrounding subsidiary cells are together called stomatal
apparatus (Figure 6.1).
Epidermal cells
Subsidiary cells
Chloroplast
Guard cells
Stomatal
pore
Figure 6.1 Diagrammatic representation: (a) stomata with bean-shaped guard cells
(b) stomata with dumb-bell shaped guard cell
The cells of epidermis bear a number of hairs. The root hairs are
unicellular elongations of the epidermal cells and help absorb water and
minerals from the soil. On the stem the epidermal hairs are called
trichomes. The trichomes in the shoot system are usually multicellular.
They may be branched or unbranched and soft or stiff. They may even
be secretory. The trichomes help in preventing water loss due to
transpiration.
6.1.2 The Ground Tissue System
All tissues except epidermis and vascular bundles constitute the ground
tissue. It consists of simple tissues such as parenchyma, collenchyma
and sclerenchyma. Parenchymatous cells are usually present in cortex,
pericycle, pith and medullary rays, in the primary stems and roots. In
leaves, the ground tissue consists of thin-walled chloroplast containing
cells and is called mesophyll.
Reprint 2025-26
