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On the bark of an oak there is a layer of grey green fronds, branching like miniature antlers. This is Evernia prunastri, oakmoss, though biologically it is not a moss. Extracted with a solvent, that lichen gives a damp, earthy, dry grass smell that underpins a whole family of perfume.

A lichen on the oak

The name oakmoss is a familiar name rather than an accurate one. Evernia prunastri is a lichen, a living partnership of fungus and alga, with no roots and no flowers, clinging to bark and drawing water from humid air. It grows on oak and some other trees in temperate Europe and North America.

The raw material for perfumery is harvested mainly in the Balkans and Morocco. The lichen is pulled from the bark, dried, then sent on for extraction. France, especially Provence, has long been the main place of production for the extract.

The library describes the smell of oakmoss as woody, earthy, damp, dry grass, with an almost metallic depth. The Chypre family page adds an inky facet: damp, bitter, slightly salty, slightly smoky. Perfume language has its own word for that whole region of smell: mossy.

No leaf, no flower, no peel. Only a grey layer of fronds on a trunk. Yet that layer has served as a foundation for European perfume for more than a century, and it is also the material whose rules have changed most over the past two decades.

Evernia prunastri and treemoss

The materials perfumery calls moss actually come from two different lichens. Oakmoss is Evernia prunastri. Treemoss is Pseudevernia furfuracea, growing on trees in temperate Europe, both oak and conifers. The two look alike, and in perfumery they are usually mentioned together.

Oakmoss extract is made with a solvent. The dry lichen is extracted with hexane to a concrete, then washed with alcohol to give an absolute. There is no common distilled essential oil of oakmoss: its scent lies in heavy, low volatility molecules that steam cannot carry far.

The composition table in the library shows why oakmoss smells as it does. The major components are methyl β-orcinolcarboxylate at 15 to 25 percent, atranorin at 5 to 15 percent, methyl β-orsellinate at 3 to 10 percent, along with atranol and chloroatranol. Most are heavy aromatic ring compounds of low volatility, which is why the smell of oakmoss arrives slowly and stays long.

Treemoss has a different composition, with physodone and its derivatives, but it also contains atranol and chloroatranol. The library lists its skin sensitisation risk as very high, with a recommended dermal maximum of 0.1 percent, and the limit is counted together with oakmoss when both materials are in one formula.

Oakmoss in the chypre structure

A perfume structure sometimes carries the name of a single bottle. In 1917 François Coty released a perfume called Chypre, the French name for Cyprus. Its recorded structure is bergamot at the top, rose and jasmine in the heart, and oakmoss, labdanum and patchouli in the base. After that bottle, the word Chypre became the name of a whole fragrance family.

In the classification of the Société Française des Parfumeurs, Chypre is family D, built mainly on three materials: oakmoss, labdanum and patchouli. Its identifying mark is the contrast between the bright sour note of bergamot above and the damp, bitter, faintly smoky oakmoss below. The floral heart bridges those two poles.

Before 1917, oakmoss already appeared in scented preparations. Poudre de Chypre was a scented powder based on oakmoss, described by secondary sources as a hair and wig powder of early modern Europe. But only when placed beneath bergamot and flowers did oakmoss become the base of a named structure.

The Chypre family later split into seven subfamilies in the SFP table. One of them is Green Chypre, subfamily D6, which adds galbanum and leafy notes to the oakmoss frame. In this branch the scent has two layers of bitterness: the raw bitterness of leaves above and the damp bitterness of moss below. The piece chypre, bergamot, rose and damp earth goes further into building this frame with natural materials.

Atranol, chloroatranol and allergy

Two small molecules in oakmoss extract changed how perfumery uses this material. Atranol and chloroatranol are strong skin sensitisers. The composition table in the library lists atranol at 2 to 8 percent and chloroatranol at 0.1 to 2 percent in the extract.

Skin sensitisation is a delayed allergic response. The first exposure usually shows nothing. After repeated exposure, the body learns to recognise the substance as an allergen, and from then on each later exposure can bring redness, itching, dermatitis. The library's safety guide places oakmoss absolute among the oils to be kept below dermal limits, and not to be used on mucous membranes even diluted.

From 2003, the EU and IFRA began tightening limits on oakmoss. Many classical perfumes had to be reformulated. Then Regulation (EU) 2017/1410 placed atranol, chloroatranol and another substance, HICC, in Annex II, the list of substances prohibited in cosmetics. From 23 August 2019 new products containing them could not be placed on the EU market; from 23 August 2021 existing products also had to be withdrawn.

Oakmoss and treemoss extracts are also on the EU list of fragrance allergens to be named on the label, above 0.001 percent in leave on products or 0.01 percent in rinse off products. Naming allows someone who already knows a skin sensitivity to oakmoss to read the label and avoid it.

Low atranol oakmoss

Regulation did not erase oakmoss from perfume. It changed how the material is made. Oakmoss used today is a grade processed to reduce atranol and chloroatranol, usually called low atranol, or made through molecular distillation to strip those two substances out.

The IFRA Standard for oakmoss extracts sets two layers of limits. The first sits within the material itself: atranol and chloroatranol must each stay below 100 ppm in the extract. The second sits in the finished product: the amount of oakmoss extract in fine fragrance, IFRA category 4, must not exceed 0.1 percent. The piece one set of standards for every bottle explains how IFRA divides products into such categories.

A figure of 0.1 percent sounds very small. Yet oakmoss is a powerful material, and in many classical chypres its role was to give depth at the base rather than to take up space. Perfumers today work inside that narrow range, often leaning more on patchouli, vetiver and labdanum to keep the damp, dark ground.

Because atranol and chloroatranol contribute part of the smell, low atranol oakmoss is not quite the same as the older grade. The library's Chypre family page notes that it smells lighter, with less of the inky facet. A chypre bought today and a bottle of the same name from before 2003 may therefore differ precisely in the base.

The smell of damp earth today

A blotter dipped in low atranol oakmoss still gives the recognisable smell: earth after rain, damp bark, dry grass, a little salt. The smell arrives slowly and stays long. It does not open like citrus but reveals itself gradually, once the top notes have gone.

After 2000, many formulas cut oakmoss sharply and leaned more on patchouli, woods and synthetics. The trade press often calls this group modern chypre. It is a common term, not a subfamily in the SFP table. The family keeps its name, but the weight at the base has shifted.

Such changes are not always visible to the wearer. The name stays the same, the packaging stays the same, only the base of the scent differs. For the perfumer, regulation becomes a material condition like any other: like volatility, like price, like the harvest season.

The Rêu Sồi perfume in the Lê Mai cabinet is one reading of this material under today's conditions. The smell of damp earth is still there, only measured in smaller numbers.

A rootless lichen became the base of a whole family.

Regulation did not erase the material. It changed how the material is made.

The base of the scent is now measured in ppm.