This is Evernia prunastri, commonly known as oakmoss. This simple lichen, native to temperate climates, tends to grow on oaks, but it’s quite adaptable. For example, the 60-year-old azalea in my front yard here in Seattle is lousy with it.
It’s also the keystone note to two of the most successful, ubiquitous, and famous accords in perfumery: the chypre and the fougère. The basic chypre accord consists of bergamot, oakmoss, and labdanum notes. The basic fougère is lavender, oakmoss, and coumarin. Both have oakmoss at their hearts.
In 1991 the perfume landscape was dramatically altered when IFRA, the European body that sets guidelines for the safety of fragrance ingredients, set strict limits on the amount of oakmoss that a perfume could contain: one tenth of one percent. IFRA set the limit after conclusive evidence showed that oakmoss -- despite being 100% all-natural, vegan, and organic — is an allergen that can irritate the skin and mucous membranes, among other things. (More specifically, the allergens in natural oakmoss are atranol and chloratranol.)
As a result of the new classification of oakmoss as an allergen, countless perfumes had to be reformulated to reduce their use of the note. For perfume nerds, these reformulations were the equivalent of repainting the Mona Lisa or redecorating the Sistine Chapel. Monuments to perfumery such as Guerlain Mitsouko (1919, by Jacques Guerlain), Christian Dior Miss Dior (1947, by Jean Carles and Serge Heftler Louiche), Robert Piguet Bandit (1944, by Germaine Cellier), and hundreds of others were changed. Depending on the scent and the zeal of one’s opinion, these changes ranged from tweaks to the utter ruination of masterpieces.
Allergen classification and IFRA regulations aren’t the only reason perfumes are reformulated, and in my opinion IFRA is somewhat unfairly vilified in the perfume world. Other reasons perfume formulae are changed include ingredient prices and availability, attempts to suit contemporary tastes, and even whim.