Mercurialis perennis, commonly known as dog's mercury, is a woodland plant found in much of Europe as well as in Algeria, Iran, Turkey, and the Caucasus, but almost absent from Ireland, Orkney and Shetland. A member of the spurge family (Euphorbiaceae), it is a herbaceous, downy perennial with erect stems bearing simple, serrate leaves. The dioecious inflorescences are green, bearing inconspicuous flowers in March and April. It characteristically forms dense, extensive carpets on the floor of woodlands and beneath hedgerows.