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Mercurialis perennis - L.

Common Name Dog's Mercury
Family Euphorbiaceae
USDA hardiness 4-8
Known Hazards All parts of the plant are poisonous[4, 65, 76].
Habitats Woods and shady places, usually in beech and oak woods, avoiding acid soils[4, 9, 13, 17, 31].
Range Europe, including Britain, from Scandanavia south and east to Spain and S.W. Asia.
Edibility Rating    (0 of 5)
Other Uses    (2 of 5)
Weed Potential No
Medicinal Rating    (1 of 5)
Care (info)
Fully Hardy Moist Soil Full shade Semi-shade
Mercurialis perennis Dog

Mercurialis perennis Dog


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Physical Characteristics

 icon of manicon of flower
Mercurialis perennis is a PERENNIAL growing to 0.3 m (1ft) by 1 m (3ft 3in) at a fast rate.
See above for USDA hardiness. It is hardy to UK zone 4 and is not frost tender. It is in flower from February to April, and the seeds ripen from May to June. The species is dioecious (individual flowers are either male or female, but only one sex is to be found on any one plant so both male and female plants must be grown if seed is required). and is pollinated by Wind, flies. The plant is not self-fertile.
Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in full shade (deep woodland) or semi-shade (light woodland). It prefers moist soil.

UK Hardiness Map US Hardiness Map



Woodland Garden not Deep Shade;

Edible Uses

Edible Parts: Oil
Edible Uses: Oil

None known

References   More on Edible Uses

Medicinal Uses

Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.
Emetic  Homeopathy  Ophthalmic  Purgative  Warts  Women's complaints

Dog's mercury is poisonous in the fresh state, though thorough drying or heating is said to destroy the poisonous principle[4]. The fresh juice of the whole plant is emetic, ophthalmic and purgative. It is used externally to treat women's complaints, ear and eye problems, warts and sores[4, 9, 21]. A lotion made from the plant is used for antiseptic external dressings[4]. A homeopathic remedy is made from the plant[9]. It is used in the treatment of rheumatism, dropsy, diarrhoea and disorders of the gall bladder and liver[9].

References   More on Medicinal Uses

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Other Uses

Dye  Oil

A fine blue dye is obtained from the leaves[1, 4, 115], it is turned red by acids and destroyed by alkalis but is otherwise permanent[115]. It resembles indigo[115]. A yellow dye is obtained from the leaves[61]. The seed is a potential source of a very good drying oil[61].

Special Uses

Scented Plants

References   More on Other Uses

Cultivation details

Prefers a humus rich soil[13, 17]. Dog's mercury is a very invasive and common hedgerow plant, it should not be necessary to cultivate it. Male and female plants usually grow in separate clumps, the females being less common[4]. The leaves contain trimethylamine and, in the early stages of putrefaction or when bruised, they give off the smell of rotting fish[245]. Dioecious. Male and female plants must be grown if seed is required.

References   Carbon Farming Information and Carbon Sequestration Information

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Seed - the plant shouldn't need any help in spreading itself, but if you are desperate to be completely overrun by it then you could spread the seed around when it is ripe in late spring and early summer. Division - once again, there really is no need to help the plant but you can divide the roots at any time of the year.

Other Names

If available other names are mentioned here

Native Plant Search

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Found In

Countries where the plant has been found are listed here if the information is available

Weed Potential

Right plant wrong place. We are currently updating this section. Please note that a plant may be invasive in one area but may not in your area so it’s worth checking.

Conservation Status

IUCN Red List of Threatened Plants Status :

Related Plants
Latin NameCommon NameHabitHeightHardinessGrowthSoilShadeMoistureEdibleMedicinalOther
Mercurialis annuaAnnual MercuryAnnual0.5 -  LMHNM111
Mercurialis leiocarpa Perennial0.1 -  LMHSNM002

Growth: S = slow M = medium F = fast. Soil: L = light (sandy) M = medium H = heavy (clay). pH: A = acid N = neutral B = basic (alkaline). Shade: F = full shade S = semi-shade N = no shade. Moisture: D = dry M = Moist We = wet Wa = water.


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Botanical References


Links / References

For a list of references used on this page please go here

Readers comment

John McInerney   Sun Mar 4 2007

Although all the references invariably state that Dog's Mercury is poisonous, my dog's (large, Bernese Mountain crossbreeds)regularly eat it, and specifically by choice when there is a range of other vegetation it would seem, when walking through our woods. How might this be explained. Is it poisonous to ruminants and humans but not to dogs, perhaps? The info above refers to it being used as an emetic - perhaps the dogs are using it for this purpose instead of the normal one of eating grass?

Ken Fern, Plants for a Future   Mon Mar 5 2007

I think it most likely that the dogs are using it to cleanse their systems, though I have never heard of this before. Most animals, with a notable exception when it comes to humans, have quite a good though not infallible, ability to sense what is good for them and what is harmful. Unless they seem to be unwell after eating it, I would tend to let them alone.

Richard Smith   Sun Jun 24 2007

My dog - a Border Terrier - also eats Dogs Mercury. When we are on a woodland walk he eats rather a lot of it and like John's dogs he chooses Dog's Mercury rather than any other plant. About half an hour after eating it my dog is sick. I've often wondered why he eats the plant every time he gets the chance rather than specific times when he might need to clear the contents of his stomach.... He's a healthy dog so sure there's no bad side effects.

Sheila Bell   Thu Oct 23 2008

I live next to semi ancient woodland which is full of dog's mercury. I regularly walk my donkeys through the wood. In Spring the donkey's will not touch the plant,but in the autumn they eat lot's of it with no ill effects. Donkeys usually know what is good for them,and what is bad...so surely it must not be poisonous in the autumn? S Bell

janet   Mon Aug 24 2009

My English Bull Terrier carefully selects Dogs Mercury in the woods and gently bites the tips off chosen leaves. It does not seem to make him sick and I have always wondered if he was self medicating.

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