Dog's Mercury

Mercurialis perennis

Herbs gallery - Dog's Mercury

Common names

  • Dog's Mercury

The dog's mercury is a foul smelling perennial plant that has a rotund and furrowed stalk. This herb bears coarse, profound green hued leaves that grow opposite to one another on the stems. The leaves are oval-shaped and dented along the borders. The blooms of dog's mercury are small and green colored and grow from the leaf axils. They blossom throughout spring.

According to the ancient scriptures, dog's mercury possesses extraordinary healing properties that have been reportedly discovered by the Roman god Mercury. In fact, the dog's mercury is a venomous plant that produces a pungent flavoured sap that was earlier prescribed by herbal medical practitioners as an antiseptic and also to remove warts or lumps from the body. However, the fetid-smelling plant is hardly used for its medicinal properties any more.

It is interesting to note that the dog's mercury got its name from the myth that the medicinal properties enclosed by this fetid-smelling plant were discovered by the Greek god Mercury. Hence, this herb is known as the mercury's grass in Greece. On the other hand, the French have named the plant la mercuriale, and the Italians call it mercorella - all names related to the Greek god Mercury. According to many experts, the term 'dog' was attached to the plant's name and it came to be called dog's mercury or dog's cole perhaps owing to the fact that it is an inferior variety compared to other plants having mercury in their name and is not edible. In fact, the other plants such as annual or garden mercury and another plant familiar to the herbalists - English mercury are all superior to dog's mercury. The last variety, English mercury was consumed in many regions of North America as a substitute for vegetables. It may be mentioned here that the prefix 'dog' was usually added to the names of flowers that were inferior to others belonging to the same species. Like 'dog violet', 'dog rose' and others, they either lacked in aroma or other properties.

The venomous properties of dog's mercury have been known to us from the records maintained by one of the first English naturalists called Ray. According to Ray, if anyone boils and consumes dog's mercury with fried bacon by mistake, this spinach like substance leads to diseases, lethargy and convulsions. Another case recorded by Ray states that when a group of vagabonds collected and boiled dog's mercury in a soup and consumed it, they all experienced the common symptoms of tranquilizing and painful poisoning. Unfortunately, two children of the group who had consumed the venomous soup breathed their last on the next day.

Many old books on plants suggest that dog's mercury may be grown as a fine potherb, but this is perhaps owing to the fact that the writers mixed up this foul smelling toxic plant with other less detrimental perennial species such as the Gerard the French or the garden mercury.

Parts used



Legendary Greek naturalists like Hippocrates recommended the use of dog's mercury for female disorders and advised people to apply the herb externally. Another well-known herbalist Culpepper also supported the use of dog's mercury for healing tender and watering eyes, deafness and even ear aches. According to Culpepper, the herb may be used as a decoction prepared with 'water and cock chicken' for treating burning convulsions during fevers. In earlier times, herbalists also used the herb to cure ailments like jaundice and even as a laxative. Freshly collected sap of the complete dog's mercury when the plant is in bloom may be blended with sugar or vinegar and applied externally to cure warts or moles as well as heal irritating and excreting wounds. Poultice prepared with the plant may also be used to treat swellings and rinse wounds and abscesses that have been persisting for long.

A cream or ointment prepared from the plant is applied as an effective antiseptic in external bandages. The lotion is applied in a similar way as carbolic is used in such conditions. In addition, the sap obtained from the dog's mercury plant may also be used as a douche in the nose to heal phlegm.

The leaves and stalks of the dog's mercury plant release an excellent blue color, much like indigo, when they are soaked in water for long. This coloring substance is basically permanent in nature, but can be transformed into red when it comes in contact with acids or destroyed by the addition of alkalis. If some method to preserve the coloring substance enclosed in the dog's mercury leaves and stems is developed, it may be used as a dye. The stems of the dog's mercury plant have an intense metallic blue hue resembling indigo and it has been found that the part that goes into the ground encloses most of the coloring substance.

When it is fresh, dog's mercury is very poisonous. However, it is said that when the plant is dried or heated, it loses its source of poison. The juice extracted from the fresh whole plant possesses emetic, purgative and ophthalmic attributes. Dog's mercury is employed topically for treating problems related to women, eye and ear disorders as well as sores and warts. An ointment prepared from the herb dog's mercury is utilized in topical antiseptic dressings. In addition, this plant is also used to prepare a homeopathic remedy, which is used to treat diarrhea, dropsy, rheumatism and disorders related to the liver and gall bladder.

The leaves of dog's mercury yield an excellent blue dye, which turns red when it interacts with acids and is obliterated by alkalis. Apart from these two changes, this dye is permanent and bears a resemblance to indigo. The leaves of this plant also yield a yellow dye, while the seeds of dog's mercury are a probable resource of a drying oil of outstanding quality.

Habitat and cultivation

The dog's mercury is indigenous to the European continent and is normally found growing in plenty in the woodlands and in shaded grounds. The herb also grows naturally or wild in the eastern regions of the United States.

Dog's mercury plant has a preference for soil rich in humus. As dog's mercury is an extremely invasive and widespread hedgerow plant, it is not necessary to cultivate this plant. Generally, the male and female dog's mercury plants grow in detached clusters - the female plants usually being less widespread. Chemical analysis of the plant has revealed that its leaves enclose a substance called trimethylamine and, during the initial stages of decay or when the leaves are bruised, they emit a smell akin to that of rotten or decomposed fish. The plant is dioecious (having separate sexes) and in order to obtain its seeds, it is essential to grow both male and female plants of the species.

As it is a very invasive plant, it usually does not require any assistance in propagating itself. Nevertheless, in case you are determined to be swamped by this plant, all that you require doing is scatter the seeds of dog's mercury around when they are mature sometime between the later part of spring and early part of summer. Dog's mercury can also be propagated by means of root division, if you really want to be infested by the plant. You may undertake root division of dog's mercury throughout the year.


Chemical analysis of dog's mercury has shown that the entire plant contains a wide range of substances, including alkaloids, sterols, terpenes plus common aromatic compounds, which are structurally different.


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