BOTANY
What is plant anatomy ?
·
Plant anatomy is
the study of what's inside plants. It looks at their different parts like
roots, stems, leaves, flowers, and fruits.
What is cell?
·
Cells are the
basic units of life.
What is tissue?
What is organ?
·
An organ is a
part of the body made up of different tissues that work together to perform a
specific function.
TYPES OF PLANT TISSUE
There are two types of
plant tissue:
1. Meristem Tissue
2. Permanent Tissue
1.
Meristem tissue
Meristem tissue
is the group of similar cell and where cells actively divide and multiply. It's
responsible for plant growth, development, and the formation of new tissues.
a.
On the basis of
plane of cell division
b. On the basis of origin
A.On
the basis of plane of cell division
1. Mass meristem
2. Plate meristem
3. Rib meristem
1.
Mass meristem:
It is type of
meristem tissue in which cell divide in all planes and increase the volume of
plant.
2.
Plate meristem
it is also the type of the meristem
tissue in which cells divides in two plane and increase the area of plant.
3.
Rib meristem
B) On The basis of origin:
1. Primary meristem
tissue
·
Apical meristem:
Apical meristem tissue is like a
plant's tip where new cells are made, helping the plant grow taller and develop
new parts.
·
Intercalary
meristem: Intercalary meristem is like a plant's middle
manager. It's the tissue that adds new growth in between existing parts, like
leaves and stems.
·
Lateral
meristem: Lateral meristem tissue
is like a plant's width booster. It helps the plant grow thicker by adding
cells to its sides, increasing its girth.
2. Secondary meristem tissue:
Secondary meristem tissue is like a
plant's repair crew. It creates new growth in older parts, helping the plant
heal wounds and build thicker layers, like wood.
Write
the function of meristem tissue?
Ø Meristem tissue is like a growth engine for plants.
It makes new cells that help plants get bigger.
Ø It creates cells for roots to reach into the soil
and for stems and leaves to stretch towards the sun.
Ø If a plant gets hurt, meristem tissue makes new
cells to repair the damage. It's like the plant's own healing team.
Ø Meristem helps plants make new branches, leaves, and
even flowers. It's responsible for their shape and structure.
Ø This tissue can adapt and change based on what the
plant needs, whether it's growing taller or wider, or recovering from harm.
What is permanent tissue?
Ø Permanent tissue is group of similar and dissimilar cell and made of cells that have settled into their roles and don't divide anymore.
1.
Simple permanent tissue
Ø Simple permanent tissue the tissue made up of
similar group or dissimilar group of non-dividing cell, they perform similar
function.
·
Parenchyma: Parenchyma
is a type of simple permanent tissue that makes a major part of ground tissues
in plants, where other tissues like vascular tissues are embedded.
·
Collenchyma: it
is living permanent tissue with the deposition of cellulose and pectin.
· Sclerenchyma: It is a simple highly thick walled dead tissue. It content fiber and sclereids.
Complex permanent tissue:
There
are two types of complex permanent tissue
1.
Pholem: Phloem
is like a plant's food delivery system. It moves the sugary nutrients produced
in the leaves to other parts of the plant so it can grow and stay energized.
2. Xylem: The vascular tissue in plants which conducts water
and dissolved nutrients upwards from the root and also helps to form the woody
element in the stem.
ANATOMY OF PRIMARY DICOT ROOT
A young dicot root
consist of this following internal feature:
Epiblema (Root Hair Zone):
·
Outermost layer
of the root.
·
Consists of root
hairs that increase surface area for water and nutrient absorption.
·
Responsible for
water and mineral uptake from the soil.
Cortex:
·
Layer beneath
the epiblema.
·
Composed of
parenchyma cells.
·
Stores nutrients
and facilitates radial movement of water and nutrients.
Endodermis:
·
Single layer of
cells surrounding the vascular cylinder.
·
Contains the
Casparian strip, a waxy barrier regulating water and nutrient entry.
·
Controls
selective passage of substances into the vascular tissue.
Pericycle:
·
Cell layer just
inside the endodermis.
·
Gives rise to
lateral roots and contributes to root thickening.
·
Plays a role in
secondary growth and root development.
Vascular Bundle:
·
Arrangement of
xylem and phloem tissues for nutrient transport.
·
Located in the
center of the root.
·
Xylem carries
water upward, while phloem transports nutrients downward.
Conjunctive Tissue:
·
Connects
different vascular bundles within the root.
·
Contains
supportive cells like fibers and sclerenchyma.
·
Provides
structural support to the root and helps withstand mechanical stress.
Pith:
·
Central region
of the root.
·
Made up of
parenchyma cells.
·
Stores food and
water, contributes to structural integrity.
ANATOMY OF MONOCOT ROOT
Epiblema (Root
Epidermis):
·
Outermost layer of the root.
·
Covered by a single layer of cells.
·
Acts as a protective barrier and helps in water
absorption.
Cortex:
·
Tissue layer beneath the epiblema.
·
Composed of parenchyma cells.
·
Stores nutrients and supports radial movement of
substances.
Endodermis:
·
Single cell layer surrounding the vascular cylinder.
·
Contains the Casparian strip, a waterproof barrier.
·
Controls the flow of water and minerals into the vascular
tissue.
Pericycle:
·
Layer just inside the endodermis.
·
Gives rise to lateral roots and contributes to root
thickening.
·
Can undergo cell division to regenerate the root's
growth.
Vascular Bundle:
·
Arrangement of xylem and phloem tissues for transport.
·
Found in the center of the root.
·
Xylem carries water, while phloem transports nutrients.
Conjunctive Tissue:
·
Connects vascular bundles in the root.
·
Contains fibers and supportive cells.
·
Provides strength and flexibility to the root.
Pith:
·
Central region of the root.
·
Consists of parenchyma cells.
·
Stores nutrients and contributes to the root's overall
structure.
ANATOMY OF DICOT STEM:
1.
Epidermis:
·Outermost
layer of the stem.
·Consists
of single layer of cells.
·Acts
as a protective barrier and allows gas exchange.
2.
Cortex:
·Tissue
layer beneath the epidermis.
·Composed
of parenchyma cells.
·Stores
nutrients and provides support.
3.
Hypodermis:
·Layer
under the cortex in some dicot stems.
·Contains
collenchyma cells.
·Offers
structural reinforcement.
4.
Pericycle:
·Cell
layer adjacent to the endodermis.
·Gives
rise to lateral roots and secondary growth.
·Can
generate new vascular tissue.
5.
Vascular Bundle:
·Arrangement
of xylem and phloem tissues for transport.
·Scattered
throughout the stem.
·Xylem
moves water, while phloem transports nutrients.
6.
Endodermis:
·Single
cell layer surrounding the vascular cylinder.
·Features
the Casparian strip, controlling nutrient entry.
·Regulates
water and solute movement in vascular tissue.
7.
Medullary Rays:
·Vertical
bands of parenchyma cells.
·Connect
the pith to the cortex.
·Aid
in lateral transport and storage.
8.
Pith:
·Central
region within the stem.
·Composed
of parenchyma cells.
·Stores
reserves and provides structural support.
ANOTOMY OF MONOCOT STEM
1. Epidermis:
·
Outermost layer
of the stem.
·
Composed of a
single layer of cells.
·
Provides
protection and enables gas exchange.
2. Hypodermis:
·
Layer beneath
the epidermis in some monocot stems.
·
Contains
collenchyma cells.
·
Offers
structural reinforcement.
3. Ground Tissue:
·
Tissue layer
beneath the epidermis or hypodermis.
·
Made up of
parenchyma cells.
·
Functions in
storage, support, and photosynthesis.
4. Vascular Bundle:
·
Arrangement of
xylem and phloem tissues for transport.
·
Scattered
throughout the stem.
·
Xylem transports
water, while phloem moves nutrients.
ANATOMY OF DICOTCOT LEAF:
1. Epidermis:
·
Outermost layer
of the leaf.
·
Comprises upper
and lower epidermis.
·
Provides
protection and regulates gas exchange.
2. Mesophyll Tissue:
·
Tissue layer
between the upper and lower epidermis.
·
Divided into
palisade mesophyll (upper) and spongy mesophyll (lower).
·
Responsible for
photosynthesis, gas exchange, and storage.
3. Vascular Bundle (Xylem and Phloem):
·
Arrangement of
xylem and phloem tissues for transport.
·
Embedded within
the mesophyll tissue.
·
Xylem transports
water, while phloem moves nutrients.
ANOTOMY OF MONOCOT LEAF
1. Epidermis:
·
Outer layer of
the leaf.
·
Comprised of
upper and lower epidermis.
·
Provides
protection and controls gas exchange.
2. Mesophyll Tissue:
·
Middle tissue
layer between the upper and lower epidermis.
·
Divided into
palisade mesophyll (closer to upper epidermis) and spongy mesophyll (closer to
lower epidermis).
·
Responsible for
photosynthesis, gas exchange, and storage.
3. Vascular Bundle (Xylem and Phloem):
·
Arrangement of xylem
and phloem tissues for transport.
·
Embedded within
the mesophyll tissue.
·
Xylem transports
water, while phloem moves nutrients.
SECONDARY GROWTH IN DICOT STEM
Secondary
growth in dicot roots is the process of increasing the root's thickness over
time through the activity of cambium, resulting in the growth of additional
vascular tissues (xylem and phloem).
Formation
of Cambium Ring in Dicot Stem:
Cambium, a thin layer of meristematic cells, develops between the primary xylem
and phloem in the dicot stem. This meristematic tissue is responsible for
secondary growth. It divides to produce new cells outwardly (secondary phloem)
and inwardly (secondary xylem), leading to the increase in stem girth.
Formation
of Secondary Tissue: The cambium
ring produces secondary xylem (wood) on the inside and secondary phloem on the
outside. As the cambium cells divide and differentiate, the secondary xylem
cells add to the stem's diameter and contribute to mechanical support.
Secondary phloem aids in nutrient transport.
Formation
of Annual Rings: During seasonal
growth, the cambium produces xylem cells. In favorable conditions, large,
light-colored cells form in spring, creating the "earlywood." In
harsher conditions, smaller, dark-colored cells develop in summer, forming the
"latewood." Together, these layers create annual rings that can
reveal the age and environmental history of the tree.
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