The same species of plant, grown in different growing conditions, produces a different essential oil with unique properties.
Altitude, water quality, soil fertility, the magnetic pull of the earth, methods of growing and weather are all factors which have an effect on the way the plant develops, and thereby influence the properties a particular batch from a particular country produces.
Think of it like a wine. People transport vines with them as they emigrate, and produce a wine related to, but not exactly the same, as that produced in the valley from which the vine came.
The word chemotypes describes these branches of the same family, which can do somewhat different jobs, and gives another indication of the broadness of the possibilities inherent in essential oils use.
Reference: The Fragrant Mind: Valerie Ann Worwood
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