Artemisia vulgaris (mugwort or common wormwood) is one of several species in the genus Artemisia which have common names that include the word mugwort. This species is also occasionally known as Felon Herb, Chrysanthemum Weed, Wild Wormwood, Old uncle Henry, Sailor's Tobacco, Naughty Man,Old Man or St. John's Plant (not to be confused with St John's wort).
It is native to temperate Europe, Asia, northern Africa and Alaska and is naturalized in North America, where some consider it an invasive weed. It is a very common plant growing on nitrogenous soils, like weedy and uncultivated areas, such as waste places and roadsides.
It is a tall herbaceous perennial plant growing 1–2 m (rarely 2.5 m) tall, with a woody root. The leaves are 5–20 cm long, dark green, pinnate, with dense white tomentose hairs on the underside. The erect stem often has a red-purplish tinge. The rather small flowers (5 mm long) are radially symmetrical with many yellow or dark red petals. The narrow and numerous capitula (flower heads) spread out in racemose panicles. It flowers from July to September.
A number of species of Lepidoptera (butterflies and moths) feed on the leaves and flowers; see List of Lepidoptera that feed on Artemisia for details.