Transcript الشريحة 1

Plant Anatomy
Also known as Micromprphology
of plants and plant- or
vegetable-histology, is
concerned with the
microscopic structure of the
tissues, cells and organs of
plants.
Plant tissues
A tissue is a group of coherent cells
having similar form and function and
have common origin.
Tissues are classified according to
stage of development to:
Meristematic tissue: the cells have the
ability of division.
Mature (permanent): the cells lost the
power of division.
Meristematic tissue
They characterized by:
1- Thin walled. 2- Isodiametric.
3- With dense cytoplasm.
4- With large nucleus.
5- Have proplastides.
6- No intercellular spaces.
7- No vacuole or presence of minute
ones.
8- No reserve food materials.
Classification of meristems
Apical meristems: located at the growing
points of stems and roots e.g. those
present in stem and root apices.
Intercalary meristems: present between two
permanent zone, present at base of
internodes e.g. sugarcane and maize.
Lateral meristems: present laterally and
cause increase in diameter of plant.
Different types of mature
tissues
2- Collenchyma
1- Parenchyma
4- Epidermis 3- Sclerenchyma
6- Pericycle
5- Endodermis
8- Laticiferous 7- Cork (phellem)
tissue
10- Tracheary
9- Sieve tissue
tissue
12- Secretory 11- Vascular tissue
structures
13-Nectaries
1- Parenchyma
Characters:
1- Simple living cells.
2- Have primary
cellulosic thin wall
with simple pits.
3- Have intercellular
spaces.
4- They may be
elongated,
isodiametric or
lobed.
Occurrence:
1- In cortex and pith of stems and roots.
2- Associated with xylem and phloem.
3- In leaves and fruits.
Function:
1- In aeration.
2- In photosynthesis.
3- Storage of water, protein, minerals, etc..
4- May become meristematic and divide.
2- Collenchyma
Characters:
1- Simple living tissue.
2- Have primary cellulosic thick wall
with simple pits.
3- May have intercellular spaces.
4- They are elongated cells.
Types:
Lamellar: thickening on
tangential walls.
Angular: thickening on
angles between the
cells.
Lacunar: thickening on
walls facing the
intercellular spaces.
Occurrence:
1- Under epidermis of stems.
2- Cortical tissue and pericycle of
leaves.
Function:
They are plastic tissue used for
mechanical support of soft plants.
3- Sclerenchyma
They are dead cells when mature
with thick secondary walls, they
are elastic tissue used for
mechanical support. Sclerenchyma
has two types; fibres and
sclereids.
A- Fibres
They are dead cells have pitted
walled with narrow Lumina and
pointed apices, xylary fibres are
lignified while extraxylary fibres
may be lignified or non-lignified.
B- Sclereids
They are dead cells short, isodiametric,
elongated or branched thick walled,
pitted, lignified with branched lumina.