DOG'S MERCURY

Mercurialis perennis

Spurge Family [Euphorbiaceae]

month8feb month8mar month8march month8apr month8april month8may

status
statusZnative
flower
flower8green
inner
inner8cream
petals
petalsZ0
type
typeZspiked
stem
stem8round
toxicity
toxicityZhigh
sex
sexZdioecious

13th May 2011, High Park Wood, under Whitbarrow, Cumbria. Photo: © RWD
A widespread creeping perennial that carpets woods and shady banks often to the exclusion of everything else. It is dioecious, with separate male and female plants. Often the carpets are exclusively of one sex.


16th June 2009, Great Ome, Llandudno, North Wales. Photo: © RWD
Also grows on mountains, here sheltering in a shallow gryke.


4th May 2011, Lathkilldale, White Peak, Derbyshire. Photo: © RWD
 Broad lanceolate and dark-green leaves.


2nd April 2014, Yarrow Valley Country Pk, Chorley, Lancs. Photo: © RWD
 Un-like Annual Mercury it is un-branched. Leaves, often curled when exposed to strong sun, are mainly near the top of the plant. Topped only by the flower spikes (or in this case, the fruits). These are male flowers.


8th April 2011, Hardraw, Hawes, Yorkshire Dales. Photo: © RWD
  Leaves are toothed. The as-yet un-opened male flowers are here encased by 3 green sepals forming triangular pyramids in small clusters up the flowering stalk.


25th March 2015, Chorley, Leeds & Liverpool Canal, Lancs. Photo: © RWD
 The jizz of the male plant


2nd April 2014, Yarrow Valley Country Pk, Chorley, Lancs. Photo: © RWD
 A male plant. As yet un-opened male flowers in several small tri-pyramidal clusters up the stalk, topped by opened flowers with numerous short stamens bearing creamy-yellow pollened anthers.


24th April 2012, Silverdale area, Cumbria. Photo: © RWD
 Bottom: an opened male flower with stamens and three light-green opened sepals (they lack petals). Rear of sepals displayed by top flower.


8th April 2011, Hardraw, Hawes, Yorkshire Dales. Photo: © RWD
 Stamens and a sepal. Short white hairs on stalks and leaves.


25th March 2015, Chorley, Leeds & Liverpool Canal, Lancs. Photo: © RWD
 Packaged in tetragonal compartments formed by the three sepals are the cream-coloured anthers, at first apparently nearly spherical.


25th March 2015, Chorley, Leeds & Liverpool Canal, Lancs. Photo: © RWD
 The spherical anthers can be discerned packaged within this un-opened male flower (top).
Middle shows the three sepals still closed up into a tetragon.
Lower shows the anthers opening up releasing the cream-coloured sand-like grains of pollen which splatter the plant.


25th March 2015, Chorley, Leeds & Liverpool Canal, Lancs. Photo: © RWD
 Close-up of male flower with three opened sepals here displaying perhaps 11 stamens bearing anthers.


25th March 2015, Chorley, Leeds & Liverpool Canal, Lancs. Photo: © RWD
 Anthers opening into two parts.


14th April 2015, Yarrow Valley Country Park, Chorley, Lancs. Photo: © RWD
 The female plants are definitely taller than the male plants.


14th April 2015, Yarrow Valley Country Park, Chorley, Lancs. Photo: © RWD
 The female flowers are shrouded by the leaves rather than being on extended stalks towering above the leaves as are the male flowers).


14th April 2015, Yarrow Valley Country Park, Chorley, Lancs. Photo: © RWD
 Your Author removed a leaf in order to more clearly show the female flowers. They have 3 triangular green sepals, a hairy dumbel-shaped ovary and a greenish-white two-pronged stigma.


14th April 2015, Yarrow Valley Country Park, Chorley, Lancs. Photo: © RWD
 Within the 3 sepals are 3? narrower, green petals.


14th April 2015, Yarrow Valley Country Park, Chorley, Lancs. Photo: © RWD
 The ovary swells to become the dual spherical fused fruit.


10th June 2010, Warton area, Cumbria. Photo: © RWD
 The fruits (which are on the female plants) are in pairs in smaller clusters up the stalk.


25th May 2012, Grizedale area, Cumbria. Photo: © RWD
  The fruits are fused pairs of spheres, sometimes triplets, sparsely up the stalk.


4th May 2011, Lathkilldale, White Peak, Derbyshire. Photo: © RWD
 Fused pairs of fruit. Unlike Annual Mercury which is hairless, the fruits have short white hairs, as do the leaves, stalks and stem. Leaf teeth are forwardly directed, and bluntly rounded. the fruit still have the two styles attached at the top.


4th May 2011, Lathkilldale, White Peak, Derbyshire. Photo: © RWD
 The fruits, as well as being fused to a neighbour, also have a circum-diametric nick, where presumably they split along when ripe to release the seeds. Both male and female flowers are petal-less and green. This is obviously a female plant with an open female flower consisting of three green sepals, an ovary topped by two short whitish styles.


14th April 2015, Yarrow Valley Country Park, Chorley, Lancs. Photo: © RWD
 A broken stem, it is solid, not hollow.


17th April 2015, River Dee, Aldford, Cheshire. Photo: © RWD
 Left.      Right.

Female and Male plants, a side-by-side comparison.


Not to be semantically confused with :   Mercury (  hydrargyrum) [a highly toxic heavy-metal chemical element not present in Dog's Mercury].

Easily mis-identified as : Annual Mercury (Mercurialis annua) which differs from Dog's Mercury in being branched, and lacking any hairs, the leaves are also usually a paler green and it does not grow in extensive carpets but instead singly on bare ground. The flowers are also slightly different. Whereas Annual Mercury grows mostly in the South and East, Dog's Mercury occurs throughout the UK. Other than those characteristics, the two are very similar.

No relation to : any of the Dog Violets (Viola), Dog Rose (Rosa canina) species, Crested Dogstail (Cynosurus cristatus), or any of the Dogwoods (Cornus) species [plants with similar names from disparate families].

Thrives in many shaded or semi-shaded deciduous woods on either calcareous soils or on clay (which is also alkaline) where it spreads by rhizomes carpeting the ground to the exclusion of most other plants. It is a perennial and also grows on hills where it is out in the open, but there it has much more competition and occurs in just small sheltered patches.

It is (mostly) dioecious, with male flowers and female flowers on separate plants, but can also be androdioecious (with male flowers on some plants, and bisexual ones on others). The carpets are usually wholly of one sex or the other, but it doesn't need to be fertilised to spread by underground rhizomes.

It is more poisonous than its only other relative, Annual Mercury (Mercurialis annua), which is an annual rather than a perennial. Un-like the other members of the Spurge Family (Euphorbiaceae) it does not produce a milky sap. Fresh parts of the plant are malodorous. An unstable blue dye can be extracted from both leaves and the root, this being CyanoHermidin.

From old sources the constituents are said to include MethylAmine, (CH3)NH2, TriMethylAmine, (CH3)3N, but this plant has been little-studied. However, these two substances alone might account for the reported repugnant smell when fresh stems are broken. Newer sources do not include those substances, but instead have found some corresponding silicon compounds such as several Fatty Acid-TriMethylSilyl Esters and about 60 differing Sterol TrimethylSilyl Ethers. The TriMethylSilyl moiety is -(CH3)3Si and is presumably ultimately derived from the chemical alteration of polysilicates from the rocks in the soil. Many other plants contain silicon for structural rigidity, such as Stinging Nettle and Horsetails.

Also found were Benzyl Alcohol, 2-PhenylEthanol, 4-MethoxyPhenol, (-)cis-Myrtanal, (-)-trans-Myrtanal, (+0)-cis-Myrtanal, Tocopherol, isomers of Phytadiene, the chlorophyll Pheophytin a (being Chlorophyll a minus the central Mg2= ion), Squalene, the carotenoid Lutein, and the sterols Campesterol and Stigmasterol.

PIPERIDINE ALKALOIDS - HERMIDINS


Hermidin is colourless but is readily oxidised to the so-called Hermidin Quinone which is yellow.


  Aqueous solutions of Hermidin turn briefly a deep-blue colour due to the formation of CyanoHermidin, which is deep-blue; a colour apparent when either young shoots or roots are cut or bruised.

  But CyanoHermidin is unstable and dimerises into the yellow-brown coloured Hermidin Dimer known as ChrysoHermidin, which can also form from the oxidation of Hermidin Dimer A, below.

  A slightly different dimer called Hermidin Dimer A (which again is yellow) can form from the dimerisation of Hermidin Quinone.


  Mercurialis perennis  ⇐ Global Aspect ⇒ Euphorbiaceae  

Distribution
 family8Spurge family8Euphorbiaceae

 BSBI maps
genus8Mercurialis
Mercurialis
(Mercuries)

DOG'S MERCURY

Mercurialis perennis

Spurge Family [Euphorbiaceae]