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Essential Oils, Glandular Trichomes & the Secondary Metabolism
by Kyle L. Ladenburger
Have you ever wondered why plants produce those
amazing compounds that essential oils are derived from? It all has to do with
glandular trichomes—tiny, specialized, hair-like formations found on plant stems and
leaves. Kyle L. Ladenburger explains what glandular trichomes are, why certain plants
developed them, and how to enhance the production of them in your plants at home.
T
he essential oil industry is a billion-dollar-a-year
business that doesn’t show any signs of slowing down.
Essential oils derived from plants, including mint, basil
and thyme, are key ingredients in products such as medicines,
aromatic fragrances and flavorings. Demand for these
products has been the driving force behind countless research
studies conducted with the
goal of understanding how
and why plants produce these
Secondary
unique chemical compounds,
and how growers can
metabolite
enhance the production
compounds are of these compounds. The
believed to play research begins with the
glandular trichome.
“
a major role in
a plant’s ability
to adapt to the
dangers of their
environment.”
Glandular Trichomes
Glandular trichomes are
tiny, specialized, hair-like
formations found on the
epidermis of plant stems
and leaves. At the tip of the
hairs are glandular cells
that produce, store and eventually secrete exudates such as
essential oils. Nearly all plant species produce some sort of
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hair-like formation, but only about 30% of vascular plants
have the ability to create these sought-after substances.
Glandular trichomes come in several different shapes that
are highly species-specific, to the point where they are often
a characteristic used in the classification and identification
of a plant species. The different types of glandular trichome
exudates include terpenoids, phenylpropenes, flavonoids and
methyl ketones. To understand what these unique chemical
compounds are, we must first address why they are produced.
The Secondary Metabolism
Glandular trichomes are not directly connected to a plant’s
vascular system and therefore are not products of a plant’s
primary metabolism. Primary metabolites—products of