2. MADE UP OF THE FOLLOWING:
o Upper epidermis: Upper layer of cells. No
chloroplasts. Protection.
o Cuticle: Waxy layer water proofing upper leaves.
o Palisade Mesophyll: Tightly packed upper layer of
chloroplast containing cells.
o Spongy Mesophyll: Lower layer of chloroplast
containing cells. Air spaces around them.
o Lower Epidermis: Lower external layer of cells in
leaf.

3. o Vascular Bundle: Bundle of many vessels (xylem
and phloem) for transport.
o Xylem: Living vascular system carrying water &
minerals throughout plant.
o Phloem: Living vascular system carrying dissolved
sugars and organic compounds throughout plant.
o Guard Cells: Cells surrounding stomata that control
rate of gas & water exchange.
o Stomata: Opening between guard cells for gas &
water exchange.

5. EPIDERMIS
A layer of thick, tough cells on the top and bottom of leaves. Protect
the leaves
Cuticle
1. Produces a waxy layer called cutin, which protects the leaf from
dehydration
2. Increases with light intensity
Leaf hairs (Trichomes)
1. Extension of epidermal cells
2. Gives plant leaves or stems distinctive textures
3. Keep insects at bay and secretes toxic or sticky fuilds for protection

6. CUTICLE AND TRICHOMES

7. TRICHOMES

8. MESOPHYLL
Mesophyll cells are specialized for
photosynthesis. These cells in the
middle of the leaf contain many
chloroplasts, the organelles that
perform photosynthesis.

10. o Tightly packed
layer of
parenchyma
cells
o Filled with
chloroplasts
o Palisade cells
are cylindrical in
shape
PALISADE LAYER

11. o Contains less chlorophyll but
photosynthesis still takes place in
these layer
o Layer of parenchyma tissues loosely
arranged to facilitate movement of
gases
SPONGY MESOPHYLL

12. SPONGY MESOPHYLL

13. Commonly known as leaf veins.
Xylem
o Adaxial in position transport water
Phloem
o Abaxial in position transports
nutrients
VASCULAR BUNDLE

14. XYLEM AND PHLOEM

15. o Natural
openings in
leaves that
allow
transpiration
and
photosynthesi
s
STOMATA

16. o Special epidermal cells
that open and close I
response to stimuli
o Control the size of the
stomata
GUARD CELLS

17. GUARD CELL AND STOMA

19. EPIDERMIS
o Single layer of cells.
o Two parts, lower and upper epidermis.
These are called lower epidermis and
upper epidermis respectively.
o Regulates the exchange of gases ( oxygen
and carbon dioxide ).
o The cells are barrel shaped and are
arranged without intercellular spaces.

20. o Trichomes serves as protection from water loss.
o Epidermis is covered by cuticle towards outside
that protects the leaf from dessication.
o Epidermis shows multicellular hairs and minute
pores called stomata.
o Each stoma is surrounded by two specialized
kidney shaped cells called the guard cells.

21. o Stomata are present on both sides and
their number is more towards lower
epidermis.
o Epidermis gives protection, regulates
transpiration and useful for exchange of
gas.

22. LEAF EPIDERMIS (DICOT)

23. MESOPHYLL
The tissue present between
upper and lower epidermis.

24. PALISADE PARENCHYMA
Below the upper
epidermis 1-3 layers of
palisade parenchyma is
present. It shows
elongated columnar
cells with small
intercellular spaces. As
more number of
chloroplasts is present,
it is mainly useful for
assimilation.

25. SPONGY PARENCHYMA:
Part of the mesophyll towards
lower epidermis is called
spongy parenchyma. It is 3-
5 layered made up of
irregular shaped cells with
large intercellular spaces.
The cells have chloroplasts
and their number is less
than those of palisade
parenchyma. Spongy tissue
is primary useful for
exchange of gases and
secondarily for
photosynthesis.

26. VASCULAR BUNDLE
o Vascular bundles are extended in the mesophyll in the form of veins.
These are big at the base of the lamina and small towards margins
and apex.
o The vascular bundles are conjoint, collateral and closed. The xylem
is present towards upper side (adaxial) and phloem towards lower
epidermis.(abaxial).
o The vascular bundle is surrounded by a layer of specialized
mesophyll cells called bundle sheath or border parenchyma. The
cells are arranged compactly and may or may not contain
chloroplasts.
o The bundle sheath cells and grows towards upper and lower sides
called bundle sheath extensions. They help in conduction of food
materials from mesophyll to the vascular bundles.

27. DICOT LEAF

29. EPIDERMIS
o On both the sides of the leaf a single
layered epidermis is present. The
cells are barrel shaped and are
arranged compactly without
intercellular spaces.
o The epidermis is covered by cuticle
outside the epidermis.

30. o Stomata are found equal in number in both the
epidermal layers.
o Trichomes are absent. In some monocots
particularly in grasses, some upper epidermal cells
are enlarged, specialized and formed into bulged
cells and filled with water. These are called
bulliform cells or motor cells. These help in rolling
and unrolling of leaf.
o The epidermis gives protection to inner tissues,
helps in transpiration and exchange of gases.

31. LEAF EPIDERMIS (MONOCOT)

32. MESOPHYLL
The tissue present between upper and
lower epidermis is called mesophyll.
It may be made up of columnar cells
(or) spongy cells. The cells are
loosely arranged having intercellular
spaces. The cells contain chloroplasts
and perform photosynthesis.

33. VASCULAR BUNDLES
o Several vascular bundles are present in the
mesophyll in the form of veins parallelly.
o The vascular bundles are conjoint, collateral and
closed. Xylem is present towards upper epidermal
side and phloem towards lower epidermal side.

34. o Each vascular bundle is surrounded by a layer of
specialized mesophyll cells called ‘border parenchyma’
or ‘bundle sheath’.
o a. Bundle sheath cells are chlorophyllous (or) non
chlorophyllous.
o They show lignosuberised bands on their radial and
transverse walls suggesting endodermal nature.
o The tissue present on the upper and lower sides of
vascular bundles is called bundle sheath extensions.
They give mechanical strength as they are
sclerenchymatous.

35. MONOCOT LEAF

36. Dicot leaf Monocot leaf
1. More stomata towards
lower epidermis.
2. Bulliform cells are
absent
3. Mesophyll is
differentiated into
palisade and spongy
tissues.
4. Bundle sheath
extensions are
parenchymatous
1. Stomata are equally
distributed on both the
sides of leaf.
2. Bulliform cells are
present in the upper
epidermis.
3. Mesophyll is
undifferentiated.
4. Bundle sheath extensions
are sclerenchymatous.
COMPARISON

37. END OF PRESENTATION