Dog's Mercury
Mercurialis perennis
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A dull green carpet with a rank smell — and thoroughly poisonous.
An unshowy woodland perennial forming dense, uniform green carpets of upright unbranched stems with paired, toothed, oval leaves. The flowers are small and green and easily missed, with male and female on separate plants. Dog's mercury is common on the floor of older woodland and shaded hedge banks around Dumfries, often to the exclusion of everything else.
Behaviour
It spreads by creeping rhizome into extensive single-sex clones, which is why one patch may never set seed. The whole plant is poisonous, with a disagreeable smell when crushed, and is left alone by grazing animals — which is part of why it can dominate. 'Dog' in old plant names signals worthlessness: unlike true mercury, this one has no use.
When to see it
Quick facts
- Family
- Spurges (Euphorbiaceae)
- Height
- 15–40 cm
- Status
- Native; common in older woodland — and poisonous
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