Dog’s Mercury

Poisonous Poisonous Autumn Autumn Spring Spring Summer Summer

Finding large swathes of Dog’s Mercury is quite a good indication that the woodland is well established.

Hedgerow Type
Common Names Dog’s Mercury, Dog's Cole
Scientific Name Mercurialis perennis
Season Start Mar
Season End Nov
Please note that each and every hedgerow item you come across may vary in appearance to these photos.


Single, serrated, lanceolate shaped and slightly downy the leaves are opposing at regular intervals along the stem.

Male Flowers

The unopened male flowers look like small green pyramids in strings, the opened flowers are pale green/cream with the stamens sticking out from between three triangle ‘leaves’.

Female Flowers

The female flowers are double spheres with tiny ‘petals’ sticking from the top.


A single, thin, erect stem.


Woodland, hedgerow or anywhere shady.

Possible Confusion

This plant is quite distinctive, the main problem with confusion is the accidental picking of the leaves of Dog’s Mercury hidden among wild garlic or other prolific woodland plants.


Rather unpleasant.


Common in established woodland.

Medicinal Uses

This plant has no medicinal use.

Other Facts

Dog’s Mercury is a highly toxic plant in the greater Euphorbia family and the use of the word ‘Dog’s’ refers to the fact that it is not edible or inferior.


4 comments for Dog’s Mercury

  1. camille sutton says:

    On a visit to the Yorkshire Dales we were staying near a woodland. Our dog which is an Inuit Dog loved and ate a lot of the dog’s mercury in the wood without ill effect. We checked it out with the local Wildlife group and were surprised to find it was toxic. He has digestive problems but no ill effects from this!

  2. Nicole says:

    Our dog, an Australian Shephard, loves this plant as well. Has eaten it quite a few times with no ill effects. She tends to like it most in late autumn. I wonder why she wants to eat it and what it does.

  3. Sarah Dennis says:

    My dog, a cocker spaniel, finds it irresistible. It makes him sick every time he eats it.

  4. Kay says:

    I also have dogs that find this stuff irresistible, ( just like cats with catnip) they particularly go for it in spring, when just a tiny bit from the tip of the plant is guaranteed to induce vomiting within minutes….but it doesn’t deter them.
    We have had four dogs over the years and all of them have consumed it at every opportunity, ( in autumn and winter the emetic effect is less powerful) which makes me wonder if the name has a deeper meaning?
    Although it always makes them sick, there have never been any other obvious toxic effects and all our dogs have lived long lives in spite of regular consumption of the dogs mercury on our daily woodland walks.

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