Page 72 - Photosynthesis: The Green Miracle

The Leaves We Smell

The Chemistry of Smell

What is the source of the pleasant smells of the herbs we eat,
the flowers in our gardens, fruit and vegetables, and the greenery we con-
sume? Scents have many effects on human nature, such as inspiring
pleasant feelings, comforting people and improving their appetite. The
smells created as great blessings for mankind are complex chemical com-
pounds. Every scent consists of elements brought together in specific
quantities. The substances that give plants their distinctive scents are

known as essential oils and are commonly referred to by the name of the
plant they come from, such as oil of roses, or oil of thyme.
Young plants produce more oils than old ones, although old plants
contain more resin and thicker oils. After light fluids have evaporated,
even at low temperatures, what remains is concentrated oils that do not
evaporate so easily.
Research has not yet uncovered all the natural functions of these oils

in plants, but it is generally agreed that they are used to attract insects.
Plant oils are also used by humans to make fragrances, cosmetics, soap
and detergents, and in food and flavorings.
Oils form in the green parts of plants and are carried to other tissues,
particularly to the shoots and flowers, as the plant matures. When we ex-
amine how these oils come into being, we are amazed at the complex, sen-
sitive nature of the system involved. Research has determined that plants’

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