The document summarizes structural variations in the leaves of three plant species: Typha, Nymphea, and maize. For Typha leaves, it notes that the epidermis is thin to absorb nutrients from water, sclerenchyma tissues are reduced as water provides support, and air chambers are present. Nymphea leaf modifications include a flattened petiole called a phyllode with sunken stomata and vascular bundles in a ring. Maize leaves have an undifferentiated mesophyll and collateral, closed vascular bundles with larger bundles supported by sclerenchyma.

1. STRUCTURAL VARIABILITIES IN
LEAVES
PRESENTED BY
GOHIL SANJAY B
M.Sc. Sem:-2
Subject:-Botany
Paper no:-CBO-405
DEPARTMENT OF LIFE
SCIENCE
H.N.G.U PATAN

2. CONTENTS
• Structural variability in leaves of –
1. Typha
2. Nymphea
3. Maize

3. TYPHA
• Typha is a hydrophytes.
• Plants that grow in water or very wet places.
• They may be submerged or partly
submerged,floting or amphibious.
• Their structural adaptations are mainly due
to high water content and the definite supply
of oxygen.

4. Typha leaf

5. Epidermis
• In aquatic plants the epidermis is not protective
but absorbs gases and nutrients directly from
the water.
• The epidermis in typical hydrophyte has an
extremely thin cuticle,and the thin cellulose wall
permit ready absorption from the surrounding
water.
• Commonly the chloroplast are found in
epidermal cells of leaves, especially when the
leaves are very thin;these chloroplasts utilize
the weak light under water for photosynthesis.

6. Lack of sclerenchyma:-
• Submerged plants usually have few or no
sclerenchymtous tissues and calls.
• The water it self gives support to the plant,and
protects it to some extent from injury.
• Thethick walls of tissues, their density and the
presence of collenchyma in some plants give
some rigidity.

7. Minimum development of vasculae
tissue:-
• The xylem shows the greatest reduction.
• In this plants, there is a well developed xylem
lacuma in the position of xylem.
• The lacunae resemble typical air-chambers.
• The phloem is fairly well developed as compared
with the xylem. The endodermis is usually
present around stele,but it is wekly developed.

8. Development of air-chamber:-
• Chambers and passages filled with gases are
commonly found in the leaves and stems or
hydrophytes.
• The air-chambers are large, usually regular,
intercellur spaces extending through the leaf
and often for long distances through the stem.
• The spaces are usually separated by partitions of
photosynthetic tissue.the carbon dioxide that is
given off in respiration is stored in these cavity
for photosynthesis.

10. Nymphea
• The phyllode is the most interesting
modification of petiole.
• The petiole becomes flattened and leaf like.
• The flattened petiole which looks like
ordinary leaf is called phyllode.
• Usually the phyllode is isolateral, so that,
both the surface are equally illuminated.

12. Epidermis:-
• It consists of a single row of cells covered
with well developed cuticle.
• Sunken stomata are present. The margin of
phyllode possess radicaly elongated
epidermal cells covered with thick cuticle.
• Below each stomata there lies a well defined
substomatal chamber for exchange of gasese.

13. Pallisade and parenchyma:-
• Just beneath the epidermis one or two layers
of pallisade parenchyma are present which
help in photosynthesis.
• The central region is occupied by thin-walled
living parenchyma cells having well
developed intercellular spaces among them.

14. Vascular system:-
• Just like in petiole the vascular bundles from a
ring and are arranged below the palisade tissue.
• The central and marginal vascular bundles are
sufficiently big in size.
• Each vascular bundle consit of xylem and
phloem.around the central and marginal
vascular bundles well developed sclerenchyma
is found.

15. • Vascular bundles are arranged in a complete
ring the central and marginal bundles are
bigger in size.
• Pallisade tissue is present
• Radically elongated epidermal cells are found
at the margins.

17. MAIZE

18. Epidermis:-
• The epidermis is found on both upper and lower
surfaces of the leafe. The epidermal layers are
uniseriate and composed of more or less oval
cells.
• The outer wall of the epidermal cells is
cuticularized.
• The upper epidermis my be easily identified due
to the presence of xylem.

19. Mesophyll:-
• As the leaf is isobilateral the mesophyll is not
differentiated into palisade and spongy
tissues.
• It is composed of compactly arranged
thinwalled, isodiametric chlorophyllous
intercellular spaces among them.

20. Vascular bundles:-
• The vascular bundles are collateral and closed as
found in monocotyledon.
• Most of the bundles are small in size but fairly
large bundles also occurs at regulsr intervals.
• The xylem is found toward upper side in the
bundles.sclerenchyma cell occur in patches on
both ends of the large vascular bundles which
give mechanical support to the leafe.

22. Reference
• B P Pandey:-plant Anatomy