There are simple and complex tissues in plants.
Parenchyma, collenchyma, sclerenchyma, are examples of simple tissues . PlantTissues fall into two large categories: Meristematic, or Permanent
(Non-Meristematic)
Xylem and phloem are example for complex tissues.
Simple tissues have only one type of cell while complex tissues have several
different types of cells.
Parenchyma:
parenchyma is the fundamental and simple tissue in plants. Almost all the
primary structure like leaves, flowers and young stem made up of parenchyma.
Cells in parenchyma are living cells. They can be
either round, suare or polyhedral. There are different types of parenchymatous
cells.
Chlorechyma:
cells in this type of parenchyma have chloroplasts and are commonly seen in
leaves.
Aerenchyma:
air spaces are present between cells in this type of parenchyma.
This type of
parenchyma is seen in plants which float on water such plants are called
hydrophytes.
Storage tissue:
cells in this type of parenchyma store food materials. This type of parenchyma
is seen in tubers and rhizomes.
Water storage:
cells in this type of parenchyma store water – such cells are seen in desert
plants.
Collenchyma :
collenchymas is a simple living tissue.
This tissue is present in the stems of herbs and shrubs. It gives mechanical
strength and support. Cells may have chloroplasts. Cells in collenchymas are
short and square or long and fibre like with pointed ends. Cell wall is made up
of cellulose and pectin which gives. Collenchyma gives flexibility and tensile strength to the
plants.
Sclerenchyma :
sclerenchyma is a tissue with dead cells and is designed to give mechanical
strength to the plant. It also protects the parenchyma from damage due to
stretching, bending and pressure lignin is the major component in cell walls of
the cells present in sclerenchyma.
Xylem: xylem is a conductive tissue which has both
living and non-living cells. It conducts water and minerals from roots to other
parts of the plant. A part from this
xylem gives mechanical strength to plant. Xylem tissue is also helpful in
identifying the plant species.
There are three kinds of non-living cells in xylem-
they are fibers, tracheas and vessels. Xylem parenchyma is the living component
in xylem. Cell walls of the xylem cells are thick because of lignin deposition.
It is also commercially very useful.
Phloem:
phloem is also called bast or leptome. Unlike xylem, phloem is a living
tissues. Cell walls have lignin deposition. Phloem is composed of five types of
cells. They are sieve cells, sieve tubes, companion cells, phloem fibres and
phloem parenchyma.
Sieve cells and sieve tubes are long with tapering
ends. Sieve plate with one to many sieve pores is present at the ends of sieve
tubes. The conductuion of food material from leaves to other parts takes place
through phloem tissues. Besides, phloem has commercial value- bast fibres
present in phloem are used for making ropes.
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