Learn how to confidently identify dogs mercury,and stay safe in the hedgerow.
Anyone who has regularly walked in ancient woodland here in Britain will probably recognise this plant. After reading this short article you will soon be able to confidently identify dogs mercury.
This perennial plant is known as an indicator of ancient woodland here in the UK. Because of this it can point to the presence of other species that also require settled, climax woodland ecologies.
This is one of only a few native members of the large spurge family. This species, and the annual mercury (Mercurius annua) are quite distinct from the various succulent and tropical-looking members that exude a photo-toxic white sap. Dogs mercury is a common poisonous plant that all foragers who are just starting out need to know.
What’s in a name?
A number of plants have the prefix ‘dog’ given to them. In many cases it inferred a plant with no medicinal use. Dogs mercury is also a fetid, rank smelling plant.
This plant was reportedly called mercury because of its similarity in form to another plant known as mercury, but more commonly called ‘good king Henry’ or ‘Lincolnshire spinach’ (Chenopodium bonus-henricus).
The generic part of the name Mercurialis, means literally ‘of mercury’. Some online references merely suggest the plant was named in honour of the god mercury. That seems a bit wishy-washy to me.
So I side with the American University of Berkley state, whose botanical department point to it being named in honour of the renaissance Italian physician Geronimo Mercurialis (1530 – 1606).
The specific part of the name, perennis, tells us this herbaceous plant returns each year.
If you find any words that are unfamiliar to you, simply head over to our comprehensive A-Z foragers glossary.
Leaves: The leaves begin to appear in late winter. They are elliptical or ovate, dark green, approximately 3 – 8 cm long, and with a distinctive white mid vein.
The opposite pairs of leaves only appear on stems. Tiny hairs are found on both sides of the leaf.
The leaf margins are quite finely serrate-crenate, with tiny white hydathodes at the tips. Ciliate hairs are present.
Petioles: Small, anywhere from 3 – 15 mm, with thin, triangular-shaped, green stipules. The stipules are similar to those found on the stinging nettle.
Roots: Dogs mercury has rhizome roots that creep and spread to form large, dense carpets. In some places it will be the only plant in many square metres of ground.
Stems: These are pretty much round-shaped, sometimes with two ridges.
The stems are swollen above the nodes. Stems are unbranched. They are hairy to mostly hairless.
Flowers: Small catkin spikes of tiny, delicate-looking green-yellow flowers.
The flowers are dioecious, meaning that male and female flowers are on seperate plants. The flowers consist only of sepals and no petals. The anthers are yellow tipped.
Flowering season: March to May.
Habitats: Old woodland, hedgerows and green lanes are all prime sites to spot this plant. It can also be found on our uplands, at altitudes of around 1000 metres. This map from the BSBI shows the extent of its range here in Britain.
Parts used: None.
Edible and medicinal Uses: None
Other notes: I couldn’t find any modern records of human poisoning, although many instances of cattle and livestock poisoning have been documented.
It may well be the case that as a species, we have long since learnt not to eat this plant. It is known to contain saponins, as well as bitter and acrid constituents.
So, now you have learnt how to identify dogs mercury, how about learning how to identify hundreds of plants in a day? This must read, two-part article introduces the most common and important plant families for foragers here in the UK. Both part one and part two will fast track your plant I/D skills, and take your foraging to another level.
Coming up next…foraging for common hogweed.