Mugwort is Artemisia vulgaris, a tall, weedy, silver-backed perennial of roadsides and waste ground across Europe and Asia. The genus is named for Artemis and includes wormwood, tarragon and the sagebrushes; the family resemblance is in the bitter, aromatic, often thujone-bearing foliage rather than in anything showy. Mugwort is not a striking plant and has never been cultivated for beauty.
Its most substantial use is one that English-language sources routinely omit. Moxibustion (the burning of compressed dried plant material on or above acupuncture points, practised across China, Japan and Korea for many centuries), uses mugwort. The Chinese ai, the Japanese yomogi, and the moxa of the word moxibustion are this genus, generally Artemisia argyi or Artemisia princeps rather than vulgaris proper, but the same plant group. This is a continuous, documented, institutionally transmitted therapeutic tradition with a literature of its own, and it dwarfs anything in the European folklore in scale and continuity.
The plant is also eaten. Japanese kusamochi and Korean ssuk preparations use young mugwort leaves as a food colouring and flavouring, and the spring shoots are a seasonal vegetable in several cuisines.
The name is unresolved. The derivation from the drinking mug, on the basis of use in flavouring beer before hops, is often repeated and is not secure; a derivation from Old English mycg, a midge, on the basis of use as an insect repellent, is equally possible and equally unproven.