WEBVTT

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The fine details in the factory.

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Both in terms of their general structure and also when examined scientifically,

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leaves exhibit very detailed and complex systems

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specially created to ensure high-level energy production.

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In order to produce energy, the plant has to obtain heat and carbon dioxide from the outside world.

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All the structures and leaves have been arranged in such a way

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is to obtain these two elements without difficulty.

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Leaves have broad external surfaces.

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This enables the exchange of gases needed for photosynthesis to take place with ease.

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The leaf's flat shape means that all its cells are close to the surface.

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This, in turn, means that the exchange of gases is facilitated

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and that solar rays can reach all the cells engaged in photosynthesis.

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If, instead of a flat and thin structure,

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leaves came in any other geometric shape

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or else had a meaningless and haphazard form,

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then photosynthesis could only take place in those regions in direct contact with the sun.

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This would mean that plants would be unable to produce sufficient energy and oxygen.

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One of the major consequences of this would be a lack of energy on Earth.

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And the creation in leaves is by no means restricted to their shape.

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Leaf tissues are also highly sensitive to light.

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The way that plant leaves always face the direction from which solar rays reach them

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can easily be observed in potted plants.

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Leaves are plants' nuclear energy production facilities

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and are factories that produce nutrients

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and yet are also laboratories in which crucial reactions take place.

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The greater the surface of the leaf,

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the greater its ability to work.

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For example, plants with broad leaves

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tend to grow in dense tropical rainforests.

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There are very important reasons for this.

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It is very difficult for sunlight to reach everywhere

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in equal quantities in tropical rainforests made up of densely packed trees.

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This makes a greater leaf surface area essential in order to trap that light.

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In these areas where sunlight penetrates very little,

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it is vitally important for leaf surfaces to be very large

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if plants are to produce nutrients.

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By way of this feature,

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tropical plants obtain sunlight from various angles

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in such a way as to make the greatest use of it.

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In contrast,

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plants in dry, harsh environments have small leaves.

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That is because,

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under such climactic conditions,

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the main disadvantage facing plants is water loss.

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And,

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as leaf surface area increases,

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so does evaporation,

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and thus water loss.

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For that reason,

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the light trapping leaf surface

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has been created in such a way

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as to behave economically

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to best conserve water.

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Leaf restriction reaches the highest level

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in desert environments.

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Cacti, for example,

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have thorns instead of leaves.

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In these plants,

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photosynthesis is carried out in the fleshy body.

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The trunk is also where water is stored.

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However,

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this by itself is not enough to control water loss.

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No matter how small a plant's leaves may be,

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water will still continue to be lost through its pores.

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A mechanism to balance evaporation is therefore essential.

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Plants possess a means of regulating excess evaporation,

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which they do by means of controlling the apertures of their pores,

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expanding or contracting them.

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Trapping the light necessary for photosynthesis

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is not the only function performed by leaves.

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The way they also trap carbon dioxide in the air

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and transmit this to where photosynthesis is made

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is equally important.

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Plants perform this duty

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by means of the pores on the leaves.

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Plants are in-air.