NS3878 : Dog's Mercury

taken 6 years ago, near to Renton, West Dunbartonshire, Great Britain

Dog's Mercury
Dog's Mercury
These plants were growing beside a NS3878 : Path through the woods.

Dog's Mercury, Mercurialis perennis, can form a dense carpet in woods; see NS3280 : Woods at Colgrain for an example. The male and female flowers are usually borne on different plants.

The species is poisonous, containing methylamine and other toxins. As noted at the link just given, cases of poisoning have occurred when Dog's Mercury has been mistaken for the edible NJ3135 : Brooklime (Veronica beccabunga). However, the plants are really not very similar, and such cases are rare.

In the common name Dog's Mercury, "dog's" has a pejorative force; the poisonous plant is being compared unfavourably with the edible Chenopodium bonus-henricus (sometimes called "mercury", but more usually called "Good King Henry").

Dog's Mercury spreads by rhizomes, forming clonal patches. The ripe fruits also employ an explosive mechanism to ensure wider dispersal of the seeds. The plant relies on a massive rootstock (a swollen main root). The plant's smaller roots have contractile properties; this helps to ensure that the growing rootstock does not become exposed by pushing itself out of the soil. This property is particularly useful in one of the plant's other habitats, on mountain rocks, where soil cover would typically be thinner than it is in woodland.


Richard Mabey, "Flora Britannica" (1997): pp 256-257, on the plant's common name, its poisonous properties, and its clonal spreading by rhizomes.

Alastair Fitter, "Collins New Generation Guide: Wild Flowers of Britain and Northern Europe" (1987): p168 on explosive seed dispersal; p213 on the contractile roots.
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NS3878, 264 images   (more nearby )
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Date Taken
Friday, 26 April, 2013   (more nearby)
Wednesday, 1 May, 2013
Geographical Context
Woodland, Forest 
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Closeup  Life 
Subject Location
OSGB36: geotagged! NS 3845 7827 [10m precision]
WGS84: 55:58.2100N 4:35.4069W
Camera Location
OSGB36: geotagged! NS 3845 7826
View Direction
North-northeast (about 22 degrees)
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Poisonous Plant 

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