Essential oil chemotypes are produced from the same plant species but have different chemical components; they usually have different therapeutic properties for aromatherapy practice. Put simply, essential oil chemotypes are extracted from plants that belong to the same genus and species; the difference is in the internal appearance, not the external appearance, of the plant.

Essential oils extracted from the same plant species may look the same but chemically they are different. It is important to correctly identify both the plant species and the chemotype of an essential oil before using it for therapeutic purposes in aromatherapy in order to know how to use it; here’s a quick look at some of the common chemotypes of essential oils.

Essential Oil Chemotypes

An essential oil chemotype is derived from a plant that has the same visual appearance and characteristics but it is chemically composed of differing components. An essential oil chemotype has different therapeutic properties due to the presence of different chemical components; for example, one chemotype may have a higher content of alcohols compared to another chemotype that may have a high content of phenols. Chemotypes are present in both wild and cultivated plants.

Describing an Essential Oil Chemotype

Plants are more correctly identified through the use of the botanical classification system, and not the often confusing common English name. For example, rosemary is classified as Rosmarinus officinalis; to correctly identify the chemotype of rosemary the abbreviation ct. is used, followed by the chemical constituent that makes up the particular chemotype. Therefore “camphor” rosemary essential oil is correctly identified as Rosmarinus officinalis ct. camphor. Other rosemary essential oil chemotypes include:

• Rosmarinus officinalis ct. cineole: high in the chemical component 1,8 cineole.

• Rosmarinus officinalis ct. verbenone: high in the chemical components verbenone and pinene.

Why Plant Species Produce Different Chemotypes

Plant species produce different chemotypes for various reasons. Factors that may affect the production of essential oil chemotypes include:

• wild plant species may naturally cross-pollinate

• the elevation at which a plant is grown

• the growing conditions of the plant

• climate

• other environmental factors.

Lamiaceae Plant Family Chemotypes

The Lamiaceae plant family contains many essential oil chemotypes. These include:

• Rosemary (Rosmarinus officinalis): As described above.

• Thyme (Thymus vulgaris): ct. thymol, ct. linalool, ct. carvacrol, ct. thujanol-4, ct. geraniol, ct. terpineol.

• Basil (Ocimum basilicum): ct. eugenol, ct. linalool, ct.estragole.

• Sage (Salvia officinalis): ct. cineole, ct.thujone.

• Lemon Balm (Melissa officinalis): ct. citral, ct.citronellal.¹

In addition to the Lamiaceae plant family chemotypes, other plant families also have essential oil chemotypes; for example, valerian (Valeriana officinalis): ct. valeranone, ct. valeranal, ct. cryptofuranol.¹

Plant Species vs. Chemotypes

Finally, don’t be confused by plant species, genus, and chemotypes. For example, the lavender(Lavandula) species produces at least three different genus that are used in aromatherapy:

• true lavender (Lavandula angustifolia)

• lavandin (Lavandula x intermedia)

• spike lavender (Lavandula latifolia).

Although these plants (and subsequent essential oils) are made up of differing chemical components, they are not chemotypes; although they are extracted from the same species, they are not extracted from the same plant genus.

Learn More About Essential Oils with Sedona Aromatics

If you would like to learn more about essential oil chemotypes, take a look at the Sedona Aromatics Certificate in Professional Aromatherapy.

References:

1. Price, Shirley & Price, Len 2012 Aromatherapy for Health Professionals UK: Churchill Livingstone

• Author is a 20 year veteran in the health care and aromatherapy industry, a UK-certified aromatherapist, published author in aromatherapy, an approved education provider for the National Association for Holistic Aromatherapy (NAHA), an aromatherapy business owner, a consultant, and Chief Editor for the NAHA Aromatherapy Journal.

Other Reading:

• Clarke, Sue 2008 Essential Chemistry for Aromatherapy UK: Churchill Livingstone