Mercurialis perennis - Dog's Mercury - (Euphorbiaceae)

Dog's mercury is an extremely poisonous plant found in deciduous woods and hedgerows. It also grows on limestone pavements. It is considered worthless - hence its common name.

It is common and widespread in woodlands in southern England, but much less so in Scotland and Ireland. It spreads at a considerable pace and, as a result, often crowds-out other (more attractive) woodland species. This plant is also present trhoughout much of northern and central Europe including Slovenia.

Dog's mercury

Annual mercury is a weed that grows among crops in fields; it is very similar in appearance but it is not a perennial plant.

The plants on this page were photographed in woodlands in West Wales.