Support in plants through supporting tissue (paranchyma, collenchyma, sclerenchyma)

Support in plants through vascular bundles and turgor pressure
   • Support in plants, through turgor pre...  

COLLENCHYMA AND SCLERENCHYMA
In the stem, the function of support is shared among several types of cells.
The collenchyma and sclerenchyma comprise heavily lignified cells in cortex and xylem tissues, respectively.
They also give support to the plants.
1.COLLENCHYMA CELLS
(2)
have protoplasts.
are living usually lack secondary walls.
(3)
have angular thickening in their primary walls.
(4)
are usually grouped in strands or cylinders.
(5)
provide support to young herbaceous parts of the plant.
(6)
Young stems, often have a cylinder of collenchyma just below their surface.
(7)
Collenchyma cells are elastic, elongate with the growth of stems and leaves.
SCLERENCHYMA CELLS
(1)
(2)
They lose their protoplasts after maturity.
They have mostly non-living cells and contain lignin (an organic substance that makes the wall tough and hard.
(3)
They have thick secondary cell walls.
(4)
Their primary function is to provide support to the plant parts.
(5)
They are seen in only woody dicots.
TYPES OF SCLERENCHYMA CELLS:
There are three types of sclerenchymatous cells.
Fibers (Tracheids): These are long and cylindrical and they may exist as solid bundles in xylem or as bundle caps.
Sclereides: These are shorter than fibers and are found in seed coats and nut shells that provide protection.
Vessels (Trachea): Long tubular structures, join end to end to form long water conducting pipes in xylem.
VASCULAR BUNDLES
he vascular bundles containing the xylem are tough and inextensible to perform the same function as steel
rods in reinforced concrete. This arrangement as a ring within the stem provides very effective resistance to wind stress,
and weight bearing ability.
4 BUNDLE CAP:
In the stem of some plants, like sunflower, the vascular bundles are strengthened by additional sclerenchyma
fibers, which form bundle cap.