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Dog's Mercury

©Philip Precey

Dog's mercury

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Scientific name: Mercurialis perennis
Often seen carpeting the floor of ancient woodlands, Dog's mercury can quickly colonise, its fresh green leaves shading out rarer plants. It is also very poisonous.

Top facts

Stats

Height: up to 35cm

Conservation status

Common.

When to see

January to December

About

A common plant, often seen carpeting the floor of ancient woodlands, Dog's mercury can quickly colonise and spread by its underground rhizomes (stems). It can be so expansive that it shades woodland floors and crowds out rarer species like Fly orchid and Oxlip. It produces small flowers from February to April, but leaves can persist throughout the year.

What to look for

Dog's mercury has spear-shaped, toothed, fresh green leaves carried on upright stems. It produces a foul and rotten smell, and bears clusters of small, greenish flowers in spring.

Where to find

Widespread.

Did you know?

Unlike the 'true' mercuries (Chenopodiumspecies such as Good-King-Henry), Dog's mercury is highly poisonous and hence became known as 'False mercury' or 'Dog's mercury'. Ingestion of this plant can lead to vomiting, jaundice, coma and eventually death.