this slideshow will tell you about the leaf structures......

2.  A leaf is an organ of a vascular plant, as defined in botanical terms, and
in particular in plant morphology. Foliage is a mass noun that refers to
leaves as a feature of plants.
 Typically a leaf is a thin, flattened organ borne above ground and
specialized for photosynthesis, but many types of leaves are adapted in
ways almost unrecognizable in those terms: some are not flat (for
example many succulent leaves and conifers), some are not above
ground (such as bulb scales), and some are without major
photosynthetic function (consider for example cataphylls, spines,
and cotyledons).
 Conversely, many structures of non-vascular plants, or even of
some lichens, which are not plants at all (in the sense of being
members of the kingdom Plantae), do look and function much like
leaves. Furthermore, several structures found in vascular plants look
like leaves but are not actually leaves; they differ from leaves in their
structures and origins. Examples include phyllodes ,cladodes,
and phylloclades.

3.  Leaves are a plant's main photosynthetic organs. Leaf
structure is closely associated with its photosynthetic
function. Leaves must permit carbon dioxide access to
the photosynthetic cells but impede water from
diffusing out. The oxygen that is a waste product of
photosynthesis must be allowed to escape from the
leaf.

4.  Leaves have a large surface area so that they can trap
enough light for photosynthesis.
 Plants which live in the shade eg:-woodlands,usually
have very thin leaves with a very large surface area.such
plants would be unable to live in full sunlight because
they would loose water so rapidly. Furthermore, their
very thin leaves would easily be damaged in the wind.
thicker leaves would not be any better for shade plants
because the light intensity is too low for light to
penetrate into the lower spongy mesophyll. the
chloroplasts would be wasted.

5.  Plants which live in very sunny places tend
to have much thicker leaves.because the
light is so strong,it can get through the
pallisade mesophyll down to the spongy
mesophyll underneath.such plants donot do
very well in shady places because the light
intensity is too low for it to get to the lower
spongy mesophyll.
 Photosynthesis produces glucose .this can
be converted into starch and stored.

6. Waxy cuticle:-
The wax cuticle forms a waterproof layer over the leaf.it
prevents excessive water loss.it also prevents the entry
of viruses,bacteria and fungi.
 epidermis:-
The upper and the lower epidermis produce the waxy
cuticle.except for their guard cells,they do not contain
chloroplasts.the epidermis is clearly transparent.

7. Mesophyll:-
The mesophyll consists of 2 layers of photosynthetic cells:the
palisade mesophyll consists of columnar cells and the
spongy mesophyll consists of spherical cells.
Air spaces:-
There are air spaces between the cells in both spongy and
pallisade mesophyll.the air spaces in the mesophyll are
bigger and nearer to the stomata.this means that the
spongy mesophyll will get more CO2 than the pallisade
mesophyll.

8. Stomata:-
These are tiny holes in the lower epidermis.a few planrts also have
stomata on the upper surfaces of their leaves.plants living in very
wet places can afford to lose water so they tend to lose more
stomata.
Guard cells:-
Unlike the other cells in the epidermis,guard cells contain
chloroplasts.they are able to change their shape to open the close
of stoma they surround.they can close their stomata to prevent
excessive water loss in dry,hot,windy conditions.they have to
open their stomata to allow gasoues exchange.

9. Vascular bundles:-
The midrib and veins in a leaf contain vascular
bundles.each bundle contains 2 kinds of tissue.xylem
serves 2 functions.firstly,it brings water and mineral
salts from the ground in its xylem vessels.secondly,it
helps to support the leaf.phleom can bring organic
nutrients eg:amino acids into the leaf:it also carries
sucrose out of the leaf.