Sweetgrass (Hierochloe odorata) is a perennial grass with thin stems reaching 20 to 50 centimetres in height, scattered across much of Europe, Asia, and North America, favouring damp meadows and riverbanks. Its scientific name means "sacred grass" — from the Greek hierós, "sacred," and chloé, "grass." The lower part of its leaves in particular carries an intense aroma reminiscent of sweet woodruff and vanilla, one that grows even more pronounced as the grass dries. Botanically closely related is the North American bison grass (Anthoxanthum nitens, formerly also classified as Hierochloe odorata), whose name reflects bison's fondness for grazing on it; the two are today often regarded as a single, widespread species with numerous local varieties.

In parts of Prussia, the grass was dedicated to the Virgin Mary and strewn before church doors on feast days, which its German name references. In North America, where it is known as sweetgrass, it ranks among the four sacred medicines for numerous Indigenous peoples — alongside tobacco, sage, and cedar — and is traditionally burned in purification ceremonies; the three strands braided together are seen in many traditions as symbolizing mind, body, and spirit. Its long, pliable leaves have also been woven into baskets for generations, a craft still practiced today among the Wabanaki and Haudenosaunee peoples of northeastern North America. In Europe, the closely related bison grass also flavours spirits such as the Polish vodka Żubrówka — named after the European bison (żubr), which favours grazing on the plant — as well as perfumes and tobacco. The American botanist and writer Robin Wall Kimmerer, herself a member of the Citizen Potawatomi Nation, brought the grass to wide international attention with her acclaimed book "Braiding Sweetgrass," describing its significance as a teacher of gratitude and reciprocity in Indigenous thought.

Burned as incense, sweetgrass releases a sweet, warm, hay-like scent with a delicate note of vanilla. It is traditionally associated with cleansing, healing, and inviting positive energy, and in many traditions is considered a gentle close to an incense ceremony, often burned after stronger herbs such as sage. Some aromatherapists also value its scent for a calming, anxiety-easing effect, using it alongside lavender in relaxation blends.