Dog's Mercury
Encyclopedia
Mercurialis perennis, commonly known as dog's mercury, is a woodland plant found in much of Europe
, but almost absent from Ireland
, Orkney and Shetland. A member of the spurge family (Euphorbiaceae
), it is a herbaceous
, downy perennial with erect stems bearing simple, serrate leaves. The dioecious
inflorescence
s are green, bearing inconspicuous flowers in March and April. It characteristically forms dense, extensive carpets on the floor of woodlands
and beneath hedgerows.
ne (basic) soils and can be found in abundance in suitable habitats in limestone
regions. It also occurs widely on neutral soils, but is absent from acid
ic ones. Spreading by underground rhizomes, it thrives in deep shade or semi-shade, where its dense growth may shade out other woodland flowers such as oxlip
, fly orchid
, and even young ash seedlings, but in the open it eventually gives way to other plants.
Although it is strongly associated with land that has had a long continuity of woodland or shrub cover, and only rarely occurs in extensive areas of secondary woodland
, it is nevertheless able to colonise new deciduous woods on dry, calcareous soils at an annual rate of a metre or more.
Existing colonies in some parts of Britain (including some in woods on boulder clay
in East Anglia
), are expanding and showing increased vigour, perhaps as a result of deeper shade in woodlands where coppicing
has ceased.
posy.
(mercurialine) and trimethylamine
are thought to be present, together with a volatile oil and saponin
s. Symptoms of poisoning appear within a few hours; they can include vomiting, pain, gastric and kidney inflammation, and sometimes inflammation of the cheeks and jaw ("malar erythema") and drowsiness. The first-known account of this phenomenon probably dates from 1693, when a family of five became seriously ill as a result of eating the plant (after boiling and frying it); one of the children died some days later as a result.
Apart from Chenopodium bonus-henricus and some other edible members of the Chenopodiaceae
(also known as mercuries), the most similar-looking species is probably Mercurialis annua
, annual mercury, which is also thought to be poisonous. Dog's mercury has been eaten in mistake for brooklime.
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, but almost absent from Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
, Orkney and Shetland. A member of the spurge family (Euphorbiaceae
Euphorbiaceae
Euphorbiaceae, the Spurge family are a large family of flowering plants with 300 genera and around 7,500 species. Most are herbs, but some, especially in the tropics, are also shrubs or trees. Some are succulent and resemble cacti....
), it is a herbaceous
Herbaceous plant
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...
, downy perennial with erect stems bearing simple, serrate leaves. The dioecious
Dioecious
Dioecy is the property of a group of biological organisms that have males and females, but not members that have organs of both sexes at the same time. I.e., those whose individual members can usually produce only one type of gamete; each individual organism is thus distinctly female or male...
inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
s are green, bearing inconspicuous flowers in March and April. It characteristically forms dense, extensive carpets on the floor of woodlands
Understory
Understory is the term for the area of a forest which grows at the lowest height level below the forest canopy. Plants in the understory consist of a mixture of seedlings and saplings of canopy trees together with understory shrubs and herbs...
and beneath hedgerows.
Growth
Dog's mercury favours alkaliAlkali
In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Some authors also define an alkali as a base that dissolves in water. A solution of a soluble base has a pH greater than 7. The adjective alkaline is commonly used in English as a synonym for base,...
ne (basic) soils and can be found in abundance in suitable habitats in limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
regions. It also occurs widely on neutral soils, but is absent from acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...
ic ones. Spreading by underground rhizomes, it thrives in deep shade or semi-shade, where its dense growth may shade out other woodland flowers such as oxlip
Primula elatior
Primula elatior, the oxlip , is a flowering plant in the genus Primula, found in nutrient- and calcium-rich damp woods and meadows throughout Europe with northern bordes in Denmark and southern parts of Sweden, eastwards to Altai Mountains and on the Kola Peninsula in Russia...
, fly orchid
Fly Orchid
Ophrys insectifera, the Fly Orchid, is a species of orchid and the type species of the genus Ophrys. It is native to Europe and favors sites with alkaline soil. The name arises because it resembles a fly, being totally dependent on flies and bees for pollination...
, and even young ash seedlings, but in the open it eventually gives way to other plants.
Although it is strongly associated with land that has had a long continuity of woodland or shrub cover, and only rarely occurs in extensive areas of secondary woodland
Secondary forest
A secondary forest is a forest or woodland area which has re-grown after a major disturbance such as fire, insect infestation, timber harvest or windthrow, until a long enough period has passed so that the effects of the disturbance are no longer evident...
, it is nevertheless able to colonise new deciduous woods on dry, calcareous soils at an annual rate of a metre or more.
Existing colonies in some parts of Britain (including some in woods on boulder clay
Boulder clay
Boulder clay, in geology, is a deposit of clay, often full of boulders, which is formed in and beneath glaciers and ice-sheets wherever they are found, but is in a special sense the typical deposit of the Glacial Period in northern Europe and North America...
in East Anglia
East Anglia
East Anglia is a traditional name for a region of eastern England, named after an ancient Anglo-Saxon kingdom, the Kingdom of the East Angles. The Angles took their name from their homeland Angeln, in northern Germany. East Anglia initially consisted of Norfolk and Suffolk, but upon the marriage of...
), are expanding and showing increased vigour, perhaps as a result of deeper shade in woodlands where coppicing
Coppicing
Coppicing is a traditional method of woodland management which takes advantage of the fact that many trees make new growth from the stump or roots if cut down. In a coppiced wood, young tree stems are repeatedly cut down to near ground level...
has ceased.
Names
The plant's common name derives from the plant's resemblance to the unrelated Chenopodium bonus-henricus (Good King Henry, also known as mercury, markery, Lincolnshire spinach). Since Mercurialis perennis is highly poisonous, it was named "dog's" mercury (in the sense of "false" or "bad"). It has also been known as boggardBoggart
In Englishfolklore, a boggart is a household fairy which causes things to disappear, milk to sour, and dogs to go lame. Always malevolent, the boggart will follow its family wherever they flee...
posy.
Plant communities
Dog's mercury is one of the characteristic plants of several woodland types, in particular:- W8 Fraxinus excelsior - Acer campestre - Mercurialis perennis woodland
- W9 Fraxinus excelsior - Sorbus aucuparia - Mercurialis perennis woodland
- W12 Fagus sylvatica - Mercurialis perennis woodland
Chemical characteristics
Dog's mercury is highly poisonous. MethylamineMethylamine
Methylamine is the organic compound with a formula of CH3NH2. This colourless gas is a derivative of ammonia, but with one H atom replaced by a methyl group. It is the simplest primary amine. It is sold as a solution in methanol, ethanol, THF, and water, or as the anhydrous gas in pressurized...
(mercurialine) and trimethylamine
Trimethylamine
Trimethylamine is an organic compound with the formula N3. This colorless, hygroscopic, and flammable tertiary amine has a strong "fishy" odor in low concentrations and an ammonia-like odor at higher concentrations...
are thought to be present, together with a volatile oil and saponin
Saponin
Saponins are a class of chemical compounds, one of many secondary metabolites found in natural sources, with saponins found in particular abundance in various plant species...
s. Symptoms of poisoning appear within a few hours; they can include vomiting, pain, gastric and kidney inflammation, and sometimes inflammation of the cheeks and jaw ("malar erythema") and drowsiness. The first-known account of this phenomenon probably dates from 1693, when a family of five became seriously ill as a result of eating the plant (after boiling and frying it); one of the children died some days later as a result.
Apart from Chenopodium bonus-henricus and some other edible members of the Chenopodiaceae
Chenopodiaceae
Chenopodiaceae were a family of flowering plants, also called the Goosefoot Family. They are now included within family Amaranthaceae. The vast majority of Chenopods are weeds, and many are salt and drought tolerant. A few food crops also belong to the family: spinach, beets, chard, quinoa, and...
(also known as mercuries), the most similar-looking species is probably Mercurialis annua
Mercurialis annua
Mercurialis annua is a species of flowering plant in the spurge family known by the common name annual mercury. It is native to Europe but it is known on many other continents as an introduced species. It grows in many types of habitat, including disturbed areas...
, annual mercury, which is also thought to be poisonous. Dog's mercury has been eaten in mistake for brooklime.
See also
- List of early spring flowers
- Woodland and scrub communities in the British National Vegetation Classification systemWoodland and scrub communities in the British National Vegetation Classification systemThis article gives an overview of the woodland and scrub communities in the British National Vegetation Classification system.-Introduction:The woodland and scrub communities of the NVC were described in Volume 1 of British Plant Communities, first published in 1991.In total, 25 woodland/scrub...