Mugwort smudge is made from Mugwort, which is a common name for several species of aromatic plants in the genus Artemisia. In Europe, mugwort most often refers to the species Artemisia vulgaris, or common mugwort. While other species are sometimes referred to by more specific common names, they may be called simply “mugwort” in many contexts. For example, one species, Artemisia argyi, is often called “mugwort” in the context of Traditional Chinese Medicine but may be also referred to by the more specific name “Chinese mugwort”. Artemisia princeps is the Japanese mugwort, also known as yomogi (ヨモギ).
Mugworts are used medicinally, especially in Chinese, Japanese, and Korean traditional medicine. Some mugworts have also found a use in modern medicine for their anti-herpetic effect. They are also used as an herb to flavor food. In Korea, mugworts were also used for plain, non-medicinal consumption; in South Korea, mugworts, called ssuk, are still used as a staple ingredient in many dishes including rice cakes and soup.
The Anglo-Saxon Nine Herbs Charm mentions Mucgwyrt. A folk etymology, based on coincidental sounds, derives Mugwort from the word “mug”; more certainly, it has been used in flavoring drinks at least since the early Iron Age. Other sources say Mugwort is derived from the old Norse muggi, meaning “marsh”, and Germanic “wuertz”, meaning “root”, which refers to its use since ancient times to repel insects, especially moths. The Old English word for mugwort is “mucgwyrt” where “mucg-” could be a variation of the Old English word for midge “mycg”. Wort comes from the Old English “wyrt” (root/herb/plant), which is related to the Old High German “wurz” (root) and the Old Norse “urt” (plant).
Mugwort oil contains thujone, which is toxic in large amounts or under prolonged intake. Thujone is also present in Thuja plicata (western red cedar), from which the name is derived. The downy hairs on the underside of the leaves can be scraped off and used as effective tinder. All parts of the plant contain essential oils with all-purpose insecticidal properties (especially in the killing of insect larvae). This is best used in a weak infusion, but use on garden plants is not recommended as it also reduces plant growth.