Materia Aromatica

Green Herbals

Rosemary, thyme, sage and helichrysum. Herb oils read by chemotype.

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Materia Aromatica · Scent

Herb oils are commonly sold by species alone. For the herbs, species is the smaller part of the story. Thyme, rosemary and basil each occur in chemotypes, plants of one species whose oils are led by different molecules. A thymol thyme and a linalool thyme are different materials in scent, in use and in dilution.

01 · The Family

Phenols, ketones, oxides and alcohols

Most of the family comes from three plant families. The Lamiaceae supply rosemary, thyme, sage, oregano, marjoram, savory, hyssop and basil, which hold their oil in glandular hairs on the leaf. The Apiaceae supply dill herb, sea fennel, parsley and lovage, distilled from the aerial parts. The Asteraceae give helichrysum, yarrow, the artemisias, santolina and blue tansy.

Chemistry divides the herbs more usefully than botany. Phenols, carvacrol and thymol, lead oregano, savory and the strong thymes, and are sharp, hot and dominant. Ketones lead sage, the camphor rosemary and the artemisias. The oxide 1,8-cineole leads cineole rosemary and hyssop decumbens. Monoterpene alcohols and esters lead the mild thymes, sweet marjoram and clary sage, which read rounder and softer. Helichrysum stands apart, with neryl acetate and the italidiones giving a honeyed, curry-like note. Most herb oils are middle notes; the phenol and cineole types sit higher.

Phenol

Oregano and thymol thyme

Carvacrol or thymol, with para-cymene and gamma-terpinene.

Ketone

Sage and the artemisias

Thujone and camphor. Herbaceous and camphoraceous.

Oxide

Cineole rosemary

1,8-Cineole, with camphor and the pinenes.

Alcohol and ester

Mild thymes, clary sage

Linalool, linalyl acetate and terpinen-4-ol. Rounder and sweeter.

02 · The Range

Ten oils, four chemistries

No. 2830 · SpainThyme, Thymol (organic)Thymus zygis · wild-crafted organicThymol, with para-cymene and gamma-terpinene. No. 2850 · SpainThyme mild (Linalool) organicThymus zygis · wild-crafted organicLinalool and terpinen-4-ol. The mildest thyme. No. 2350 · FranceOregano, Vulgare (organic)Origanum vulgare · certified organicCarvacrol, with linalool and thymol. No. 2591 · MoroccoRosemary, Cineol (organic)Rosmarinus officinalis · wild-crafted organic1,8-Cineole and camphor, with the pinenes. No. 2620 · FranceRosemary, Verbenone (organic)Rosmarinus officinalis · wild-crafted organicalpha-Pinene and bornyl acetate, with verbenone. No. 2665 · FranceSage, Clary (organic)Salvia sclarea · certified organicLinalyl acetate and linalool, with germacrene-D. No. 2030 · EgyptMarjoram, Sweet (organic)Origanum majorana · certified organicTerpinen-4-ol and trans-sabinene hydrate. No. 1590 · FranceHelichrysum Italicum Essential Oil (Organic)Helichrysum italicum · certified organicNeryl acetate, gamma-curcumene and the italidiones. No. 1111 · EgyptBasil, 85% Methyl Chavicol (organic)Ocimum basilicum L. · certified organicMethyl chavicol, with 1,8-cineole and linalool. No. 2705 · BulgariaYarrow, Blue (organic)Achillea millefolium · wild-crafted organicSabinene, beta-pinene and 1,8-cineole.

03 · Side by Side

Three comparisons

Three thymes first. Thyme, Thymol (No. 2830), Thyme mild, Linalool (No. 2850) and Thyme, Mild, Thujanol (No. 2881) run from phenol to alcohol. The thymol oil is sharp and dominant. The linalool oil is soft and almost floral. The thujanol oil is sweet and herbaceous, between the two.

Then three rosemaries. Rosemary, Cineol (No. 2591) is led by 1,8-cineole and reads clean and penetrating. Rosemary, Borneone (No. 2610) is the camphor chemotype and reads heavier and more camphoraceous. Rosemary, Verbenone (No. 2620) carries bornyl acetate and verbenone and is the softest of the three.

Then one genus, several scents. Helichrysum Italicum (No. 1590) from France and Helichrysum Italicum, Balkans (No. 1595) share neryl acetate and the curcumenes, the Balkan oil with more alpha-pinene at the top. Helichrysum Gymnocephalum (No. 1593) from Madagascar is led by 1,8-cineole and has little of the honeyed italicum character.

04 · In Practice

Chemotype sets the format

For diffusion, cineole rosemary, sweet marjoram, the mild thymes and hyssop decumbens work well, often with conifers or citrus. In massage blends, marjoram, rosemary, clary sage, the mild thymes and helichrysum are the most widely used. In natural perfumery clary sage is a middle note that bridges lavender to amber and labdanum. Basil and thyme serve as herbal accents in colognes. Helichrysum is used in small proportion for its honeyed, tobacco-like depth.

Dilution follows the chemotype. Phenol-rich oils, oregano, savory and the thymol and carvacrol thymes, are skin irritants and are used at low dilution and never undiluted. Ketonic oils, sage, the artemisias, mugwort and santolina, are used at conservative dilution and in blends for adults only. Methyl chavicol basil is used at low concentration. The linalool and thujanol thymes carry little phenol and are the mildest of the genus.

Essential oils are for aromatic and topical use. Dilute before applying to skin. Keep out of reach of children.