Sweetgrass, known botanically as Hierochloe odorata, is a highly aromatic perennial grass revered across various cultures for its distinct scent. The plant is easily recognized by its long, slender blades, which contain a complex fragrance that intensifies upon drying. This aroma is why the grass has been historically valued, earning it common names like vanilla grass and holy grass, and making it a plant of considerable cultural importance throughout its native range in North America and Eurasia.
The Distinctive Aroma Profile
The primary scent of sweetgrass is a deep, comforting sweetness often described as being like vanilla, but more complex. This vanilla note is complemented by an undertone reminiscent of fresh hay that has been recently cut and dried under the summer sun. The combination results in a warm, clean fragrance that is both earthy and richly sweet.
Some individuals also detect nuances of sweet caramel or a faint suggestion of almond or marzipan within the overall profile. The aroma is significantly different depending on the state of the plant. Freshly cut sweetgrass has a milder, more herbaceous, and grassy scent, with the sweet notes being less pronounced.
The full, concentrated sweetness is liberated when the grass is dried, braided, or burned, which causes the scent to become notably more intense. This concentrated fragrance is described as comforting and clean, contributing to its use where a pleasant, uplifting atmosphere is desired. In perfumery, this distinct profile is sometimes referred to as foin coupé, or cut hay.
The Source of the Scent: Coumarin
The persistent fragrance of sweetgrass is attributed to the presence of a specific volatile organic compound known as coumarin. This aromatic molecule naturally occurs in the plant and is responsible for the characteristic vanilla-like and new-mown hay scent. Coumarin is also found in other fragrant plants, including tonka beans and certain types of cinnamon.
In the living grass, the coumarin is often bound within the plant’s structure, rendering it non-volatile and less noticeable to the human nose. The fragrant molecule is chemically released through a process called hydrolysis, which is initiated by the drying, crushing, or burning of the plant material. As the plant loses moisture and its cellular structure breaks down, the bound coumarin is liberated into its free, volatile form.
This mechanism explains why the sweetgrass scent intensifies dramatically after the leaves are harvested and braided. The drying process maximizes the release of the coumarin molecule, creating the potent aroma the plant is known for. Dried sweetgrass braids can retain their fragrance for many years.
Cultural and Traditional Applications
The appealing aroma of sweetgrass has made it a central element in the spiritual and practical lives of various Indigenous North American nations for centuries. It is frequently categorized as one of the four sacred medicines, alongside tobacco, sage, and cedar. The grass is traditionally braided into three-strand ropes, which are then dried and burned as a form of natural incense or smudge.
The fragrant smoke is used in purification ceremonies, with the belief that it calls in positive energy and carries prayers and intentions to the spiritual world. For many communities, the three sections of the braid symbolize important concepts like the body, mind, and spirit, or love, kindness, and honesty. This symbolic link gives the scent a meaning that transcends simple aesthetic enjoyment.
Beyond its ceremonial function, sweetgrass is also valued for its practical properties, especially its durability and appealing scent. The dried grass is historically woven into baskets, mats, and other decorative and functional items. Placed inside clothing or storage areas, the braids act as a natural sachet, infusing the contents with their unique vanilla-hay fragrance.