Class XI Unit-II

1. Chapter-6
ANATOMY OF
FLOWERING PLANTS
Presented by
B.Prabhakar
Principal
JNV. Panchmahal (Guj)

5. The tissue system
• On the basis of their
structure and location,
there are three types of
tissue systems. These
are the
1. Epidermal tissue system,
2. The ground or
fundamental
tissuesystem
3. vascular or conducting
tissue system.

7. 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 arranged cells, which form a continuous layer. Epidermis is
usually singlelayered.
• 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
beanshaped cells known as guard cells. In grasses, the guard cells are dumbbell
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 6.4).

10. GROUND TISSUE SYSTEM
• It is represented by the different regions in the plant body that are mainly involved in storage. In
the cylindrical parts of the plant body such as root and stem, the ground tissue becomes
differentiated into various regions. In a typical condition, following regions can be recognised in
the ground tissue.
• Hypodermis is a region that is found immediately below the epidermis in the stem. It is made up
of a few layers of either collenchyma cells (as in dicot stem) or sclerenchyma cells (as in monocot
stem). Hypodermis is meant for providing additional protection and mechanical support.
• Cortex is a major component of the ground tissue represented by many layers of loosely
arranged parenchyma cells. Intercellular spaces are prominent. Cortex represents the major
storage region in the plant body.
• Endodermis is the inner most layer of cortex represented by a single layer of compactly
arranged barrel-shaped parenchyma cells. In the stem, it is meant for storage. In the root it plays
an important role in the movement of absorbed water. Some of the cells in the root endodermis
contain secondary thickenings called casparian thickenings, formed by a waxy substance called
suberin.
• Pericycle is a region that lies immediately below the endodermis. In the stem, it is represented
by a few layers of sclerenchyma cells while in the root, it is represented by a single layer of
parenchyma cells.
• Medullary rays/Conjunctive tissue are represented by parenchyma cells that are found in
between the vascular tissues. In the stem, the parenchyma cells are meant for storage of food and
represent the medullary rays while in the root, they store water and represent the conjunctive
tissue.
• Pith is the innermost part of the stem or root representing the axis. It is formed by loosely
arranged parenchyma cells with prominent intercellular spaces. It is another major storage organ
in the plant body. The pericycle, the medullary rays or conjunctive tissue, and the pith along with
the vascular tissues, together represent a region, which is known as stele or central cylinder.

11. • The vascular tissue system is a derivative of procambium. It is
represented by the conducting tissues-xylem and phloem. These
vascular tissues occur in the form of vascular bundles or fascicles.
In the leaf, the vascular bundles are known as veins. The vascular
bundles may sometimes enclose a piece of meristematic tissue
called cambium, which brings about secondary growth in the
bundles.
• When cambium is present, the vascular bundle is described as open
and
• when the cambium is absent, the vascular bundle is described as
closed.
• . Accordingly, based on the relative position of xylem and phloem
the bundles can be distinguished into three types

12. Types of vascular bundles
• Conjoint Bundle
In conjoint bundle xylem and
phloem occur in the same
bundle along the same
radius.
Ex- stem, leaves
• Radial Bundle
When xylem and phloem
within a vascular bundle are
arranged in an alternate
manner on different radii, the
arrangement is called radial
Ex- root

28. Heart wood & sap wood