Reasons Why Buying Essential Oils “Just Anywhere” Can Be Problematic Reason #1) Chemotypes; Chemotype is the title given to plants that, though having the same genus and species, have very different chemical properties. For example, you could have three or more Thyme plants, each grown in a different region/ climate of France, each with a different holistic value. Why does this matter? Well, if you want Thyme for clearing lung congestion you may not get it. A bigger problem