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.
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.
9.
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.
11.
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.
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.
