Common Mugwort (Artemisia vulgaris) is a very common plant with a broad natural habitat that spreads right across the temperate regions of Europe, Asia, North Africa and North America. In some parts of the USA and in most European countries, Mugworts are considered to be invasive weeds and are little loved by gardeners.

The plant – which is also sometimes known as Common Wormwood, Wild Wormwood, Old uncle Henry, Chrysanthemum Weed, Sailor's Tobacco and (bizarrely) Naughty Man – is a herbaceous perennial with small flowers that grows up to around two metres (six feet) in height.

The English name of ‘Mugwort’ is thought likely to derive from the Old English ‘mycg’ (meaning midge) and ‘wyrt’ (meaning root or plant). It is thought that this name comes from the plant’s traditional use as an insect repellent.

Mugworts have a variety of uses in traditional medicinal practices, as well as more modern uses, and the flower buds of the plant were sometimes used to add a bitter flavour to meat and fish dishes. As well as being used to repel insects, Mugworts were often used as anthelminthics (parasitic worm removers); as a general purpose remedy for heart conditions (in Ayurveda); to terminate pregnancies (in ancient Chinese medicine, using a large dose) and to correct breech presentations (also in Chinese medicine, using smaller doses).

The plant’s more modern uses exploit the mild psychoactive and hallucinogenic properties of some of its constituent compounds, particularly those known by the chemical name of thujones. Thujones are thought to have a similar effect upon the brain as tetrahydrocannabinol (THC – the active ingredient of cannabis) and for this reason Mugwort species are often used in herbal smoking mixtures, where they are blended with other psychoactive plants such as Lion’s tail (Leonotus leonorus).

The plant also has a long history of use in medieval witchcraft, mostly because of its psychoactive properties and because it was thought to bring luck. It is thought that the plant greatly enhances dreaming – particularly lucid dreaming and the ability to control events in dreams, as well as recall dream events upon waking. It was sometimes used by proponents of ‘astral projection’, who claimed to believe that they were able to leave their bodies at will and explore the world using only their minds (or souls, if you prefer. This belief should give the reader some indication of Mugwort’s power as a hallucinogen). It is said that sleeping on a pillow filled with Mugwort can induce powerful and memorable dreams.

Because the active thujone compounds are toxic in large quantities, and because of the effects the plant can have upon pregnant women and their babies, it is generally recommended that pregnant women avoid consuming Mugwort except in very small amounts.