Page 94 - Photosynthesis: The Green Miracle

Adnan Oktar

The Sections in Leaves
Upper and lower epidermis: These two cell layers form a waxy
protective tissue. These layers, which constitute the outermost part of the

leaf, possess a very different structure produced by special cells forming
a waterproof layer over the leaf, top and bottom. Excessive water loss is
thus prevented. Excess sunlight is reflected. Thanks to this tissue, when
the pores of the plant close, the plant is able to conserve air and fluids.
The epidermis is completely transparent.
Mesophyll: This tissue consists of two layers of cells that carry out
photosynthesis. The palisade mesophyll consists of column-shaped or rod-
like cells, and the spongy mesophyll, of spherical ones. These cells contain
the chlorophylls, which are the facilities that enable photosynthesis. In ad-

dition, they also contain structures for various other functions.
Air cavities lie between both spongy and rod-like cells (the soft in-
ner tissue of the leaf). The cavities in the spongy mesophyll are larger and
closer to the air holes known as the stomata. However, this arrangement is
not coincidental. In this way, since their need for carbon dioxide is great-
er, compared to the palisade mesophyll, the spongy mesophyll receives
more of the carbon dioxide.

Pores (stomata) are small holes in the lower surface of the leaf. A
few plants also have pores on the upper surfaces of their leaves. These
pores are one of the leaves’ special components. Like windows that con-
nect the leaf to the outside world, they supervise the gasses that enter the
leaf from the air, the vapor that emerges from the leaf, and the pressure
inside it. With their other functions and the observer cells that ensure their
opening and closing, they are marvels of design.
When a tree wants to receive more or less air, it uses these pores in
the surface of its leaves, particularly the underside, which it can adjust

like nostrils. These large numbers of microscopic openings are too small
to be seen with the naked eye. Each of these is controlled by a pair of
guard cells, automatically stimulated in conditions such as moisture, light

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