Marrubium vulgare (white horehound or common horehound) is a flowering plant in the mint family (Lamiaceae), native to Europe, northern Africa, and southwestern and central Asia. It is also widely naturalized in many places, including most of North and South America.
It is a grey-leaved herbaceous perennial plant, and grows to 25–45 centimetres tall.
Horehound was introduced to southern Australia in the 19th century as a medicinal herb. It became a weed of native grasslands and pastures where it was introduced with settlers’ livestock, and was first declared under noxious weeds legislation. It now appears to have reached its full potential distribution.
It occupies disturbed or overgrazed ground, and is favoured by grazing because it is highly unpalatable to livestock. It may persist in native vegetation that has been grazed.