'New mown hay' or foin coupé perfume was popular at the turn of the 20th century, with coumarin comprising an important part of the hay-like aroma.[5] Foin coupé is actually French for ‘cut hay’ rather than the botanical name of the source plant for Hay absolute which, according to Rhind and Lawless, is an extraction of the alpine sweetgrass Hierochloe alpina[6],[7], or according to Poucher is the sweet-scented vernal grass Anthoxanthum odoratum.[8]

Chandler Burr, once a perfume critic for the New York Times, calls Hay Absolute "One of the most sublime of all perfume materials. Hay is, as literally as possible, the smell of liquid summer sunlight." Perfumers, knowing that this fragrance is not quite appealing on its own, suggest that Hay needs a ‘support group’ of mossy and green nuances to bring out its best features.

Coumarin, the aromatic lactone responsible for the sweet, hay-like aroma, is 'glycosidically bound' and not volatile when grasses are living and green, but is only liberated when the plant material is cut and dried. This is when enzymatic action occurs, breaking the chemical bonds and releasing the fragrance of a thousand blades of vernal grass.[9] Tonka Bean is another aromatic material that is noted for its coumarin content and shares scent nuances similar to some found in Hay. According to Rhind, it is noted that "Hay Absolute is often described as having a 'happy smell', and can be used for its uplifting, comforting aroma."[10]