In the Plant Body A section taken through any region of a typical plant body shows the presence of three tissue systems Epidermal Tissue System Origin It is a derivative of protoderm ID: 538826
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Slide1
TISSUE SYSTEMS
In the Plant BodySlide2
A section taken through any region of a typical plant body shows the presence of three tissue systems. Slide3Slide4Slide5
Epidermal
Tissue System
Origin -
It is a derivative of
protoderm
.
It is represented by the epidermis and the associated structures, which are mainly involved in
providing protection to the plant body. The epidermis is the outermost covering of the plant body. It is commonly described as the skin of the plant body. Slide6
In the stem and the leaf, the epidermal cells are thick-walled and are meant for protection. In the leaf, there are two epidermal layers, one on each surface of the leaf.Slide7
In the roots, the epidermal cells are thin-walled, since they are mainly involved in the absorption of water and mineral salts.
In the root, the epidermal hairs are unicellular and are called
root hairs
. The
root hairs penetrate between the soil particles to absorb water and minerals Slide8
In the stem and the leaf, the epidermal hairs are involved in the secretion of some compoundsSlide9
Structure of a leaf
PALISADE LAYER
SPONGY LAYER
STOMATA
CUTICLE
VEIN
AIR SPACESSlide10
How are palisade cells specialised?Lots of chloroplasts, which contain chlorophyll to catch light energy.Long and thin, so they pack closely together to collect as much light as possible.
They are at the top of the leaves, to get as much light as possible.Slide11
How does the carbon dioxide get inside the leaf?Slide12
The epidermis of the stem and the leaf is usually surrounded by a thin, covering called cuticle. It is formed by a waxy substance called
cutin.
It’s function is preventing excessive evaporation of water. Cuticle is absent in the root epidermis.Slide13
stomataThe epidermis of the leaf and herbaceous stem (green stem) contains numerous small openings called
stomata
.
Each stoma is surrounded by a pair of modified epidermal cells called the
guard cells
. The stomata take part in functions such as
transpiration, respiration and photosynthesis.
Stomata are absent in the epidermis of the root and woody stem.Slide14
Leaf Stomata: Allow Gas Exchange
Stomata in
Zebrina
leaf epidermis
Guard cells with chloroplasts
Stoma
Subsidiary cellsSlide15Slide16
Vascular Tissue System
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 strands extending from one end of the plant body to another. These strands are known as vascular bundles or fascicles. In the leaf, the vascular bundles are known as veins.Slide17
Vascular Tissue System
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.Slide18
Vascular Tissue System
A vascular bundle may contain either only xylem or only phloem or both
. Slide19Slide20
Xylem tissue is found in the vascular bundle in the stem. It is also found throughout the plant.Slide21
Ground Tissue System
It is a derivative
of ground meristem.
It is represented by the different regions in the plant body that are mainly involved in storage. Slide22
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
Cortex
Endodermis
Pericycle
Medullary rays
Pith
Ground Tissue System