A simple tissue is made up of one type
of cell forming a homogenous or uniform mass. Parenchyma, Collenchyma and
Sclerenchyma are the important simple permanent tissues found in plants.
Parenchyma is
the most common type of unspecilalised simple tissue. It is composed of collection
of cells which are more or less isodiametric in shape with or without
intercellular space. These are the living cells with active protoplast.
Collenchyma The
cells of this tissue are living cells with vacuolated protoplast. The most important
distinctive character of collenchyma is that either walls are unevenly
thickened or these thickenings are confined to the corners of the cells. It is
usually absent in monocot.
Parenchyma vs Collenchyma
Parenchyma
 |
Collenchyma
 |
Parenchyma
cells are present in the epidermis, cortex, pith and pericycle. Meristematic
cells are parenchymatous.
|
It occurs in the peripheral
part of elongating organs like stem and petiole, usually appearing as a continuous
ring beneath the epidermis.
|
Thin
cell wall
|
Unequally thickened cell
wall
|
Intercellular
space is present
|
Intercellular space is
absent.
|
No
pectin deposition
|
Pectin deposition is found
at the corners.
|
Shape -
Isodiametric
|
Shape - Polygonal.
|
Permanent
tissue
|
Permanent tissue sometimes
revives meristematic activity.
|
Functions:
a) Storage of food materials.
b) Chlorenchyma carries out photosynthesis.
c) Aerenchyma helps aquatic plants in floating and gaseous exchange.
|
Functions:
a) It gives mechanical support.
b) It can resist bending and stretching caused by winds.
c) It carries out photosynthesis if chloroplast are present.
|
