Plant tissues can be divided into two, namely : . 1. meristem tissue 2 . Adult tissue
MERISTEMATIC TISSUE A flowering plant has the ability to grow its entire life because it possesses...
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UNIT 4: PLANT TISSUE
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Transcript of MERISTEMATIC TISSUE A flowering plant has the ability to grow its entire life because it possesses...
UNIT 4: PLANT TISSUE
MERISTEMATIC TISSUE A flowering plant has the ability to grow its entire
life because it possesses meristematic (embryonic) tissue.
The apical meristem are located at or near the tips of stems and roots, where they increase the length of their structures by means of mitosis.
This increase in length is called primary growth.
Monocots also have an intercalary meristem, this allows them to regrow lost parts. (It is found between mature tissues). EXAMPLE: GRASS CUT - GROW
Organization of a plant body MERISTEMATI
C TISSUE AT TIP OF STEM
MERISTEMATIC TISSUE AT TIP OF ROOTS
APICAL MERISTEM Produces three types of meristems,
and these develop into the three types of specialized primary tissues in the body of the plant:
SPECIALIZED PRIMARY TISSUES: Protoderm gives rise to the
epidermis Ground meristem produced ground
tissue Procambium produces vascular
tissue
FUNCTIONS OF SPECIALIZED TISSUES
Epidermal tissue: forms the outer protective covering of a plant.
Ground tissue fills the interior of a plant.
Vascular tissue transports water and nutrients in a plant and provides support.
EPIDERMAL TISSUE
EPIDERMAL TISSUE Single layer of
closely packed, flat, brick shaped cells, with a large vacuole.
The aerial parts of the plant are covered with a cuticle.
Functions:- Cuticle minimizes water loss (because it has cutin) - Protects the plant against bacteria.
Longitudinal section
Cross section
Leaf contain upper and lower epidermal cells
SPECIALIZE EPIDERMAL CELLS
ROOT HAIR
TRICHOMES
STOMA OF LEAF
CORK OF OLDER STEMS
ROOT HAIRS
TRICHOMES
CORK CELLS
STOMATA
ROOT HAIRS They are specialized
epidermal cells of roots.
Unicellular outgrowth of the epidermal cell.
Functions: Increase the surface
area of the root for absorption of water and minerals.
Anchor the plant.
TRICHOMES Specialized epidermal
cell of stems and leaves.
Multicellular outgrowths of the epidermis of stems and leaves.
Functions: Protect the plant from
sun Conserve moisture. Protect plant from
herbivores, produce toxic substance.
CUTICLE
MULTICELLULAR
STOMATA Specialized epidermal
cells called guard cells, which are bean shaped, enclose an opening called the stoma or pore.
The guard cells contain a nucleus and chloroplasts.
It has a thick inner membrane and a thin outer membrane.
Woody plants have lenticels.
FUNCTIONS: Transpiration Gaseous exchange
take place through the stomata.
Thin outer membrane
Thick inner membrane
OPEN - DAY
CLOSED- NIGHT
GROUND TISSUE•PARENCHYMA•COLLENCHYMA•SCLERENCHYMA
GROUND TISSUES
PARENCHYMA TISSUE Occur in roots,
stems and leaves. Spherical, loosely
packed, big, thin-walled cells with large vacuoles.
Intercellular airspaces between cells.
FUNCTIONS: If they have
chloroplasts – photosynthesis.
If they have leucoplasts – they store products of photosynthesis.
They can divide to form more specialized cells
PARENCHYMA CELLS
INTERCELLULAR AIR SPACES
COLLENCHYMA TISSUE It is composed of
unevenly thickened primary walls with additional cellulose and pectin deposits especially in the corners.
Found just beneath the epidermis of young stems.
The cells are slightly elongated, tightly packed and overlap each other.
FUNCTIONS: Mechanical
strengthening and support to plant organs
SCLERENCHYMA TISSUE Cell walls have been
thickened by impregnation with lignin.
The cell wall is evenly thickened and forms a waterproof barrier impermeable to water.
In the cell walls are pit canals that serve as channels between cells and to the outside world.
The lumen is small. Two types of
Sclerenchyma: Stone cells and fibers
FUNCTIONS: Strengthening,
support and protection.
Found in shell of nuts and hard parts of fruits
Fibers give rigidity and flexibility to the plant.
VASCULAR TISSUE• XYLEM• PHLOEM
XYLEM Contains 2 types of conducting cells:
tracheids and vessel elements (VE). Both cells are hollow and non-living but the
VE is larger and has perforated plates in their end walls and are arranged to form a continuous vessel.
Tracheids have tapered ends with pits. It also has other tissue: Xylem fibers, and
Xylem parenchyma. FUNCTION: Transports water and minerals from the roots to the
leaves. Support and
strengthening.
XYLEM
PHLOEM Consist of sieve-tubes and companion cells. The sieve-tubes form a continuous tube, they have
cytoplasm but no nuclei. They have sieve plates between cells. The companion cell has a nucleus that controls
both cells because they are connected by plasmodesmata.
It also has other tissue: Phloem fibers and phloem parenchyma
FUNCTIONS: Transports sucrose and other organic substances, including hormones, from the leaves to
the roots. Support and strengthening.
METHODS TO STUDY CELLS
The microscope is an instrument designed to observe objects too small to be seen with the naked eye.
The human eye cannot distinguish objects much smaller than 0.1mm.
The microscope act as an extension of the eye, allowing one to see smaller objects.
ELECTRON MICROSCOPE
The electron microscope was developed in the late 1940’s and soon used in the study of cells.
Much more detail can be seen under an electron microscope. It can magnify parts of cells at least 300 000 times.
SCANNING ELECTRON MICROGRAPH
TRANSMISSION ELECTRON MICROGRAPH
