Hemlock (Conium maculatum)
Dear Readers, hiding in plain sight along many of our ditches and rivers is one of the most poisonous plants in the UK, Hemlock. It looks very like Cow Parsley but the leaves are different (and in my part of the world at least, it flowers a bit later).
These are the leaves of Cow Parsley (Anthriscus sylvestris). Note how fern-like they are.
Cow parsley (Anthriscus sylvestris) leaves © 2022, Philippe Juillerat – Sources du Lison
Hmm. I would say that Cow Parsley leaves tend to be more pointy and spear-like, while those of Hemlock are rounder, but it’s a tough call unless you see them side by side. Fortunately there are other identifying features:
- Hemlock is often taller
- The plant is hairless (Cow Parsley is hairy when looked at close up)
- The plant also has purple blotches and spots on its stem (hence the Latin ‘maculatum’ which means ‘spotted’. You’re welcome :-). O Level Latin has its uses!)
On the subject of the blotches, poet and naturalist Geoffrey Grigson wrote that the stalks ‘have a deadly look, as though they bore their own signature of destruction and mortification’.
Apparently it also has a mousy smell, but as we won’t be cutting any to take home (will we?) I missed that excitement.
Hemlock is an interesting plant in many ways, not least of which is that it is not a native plant, but an archaeophyte (an ancient introduction which was wild in the UK before 1492) which has made itself exceedingly at home, not just around human habitation (like so many ‘alien’ plants) but in many semi-natural habitats. In ‘Alien Plants’, Stace and Longley describe how the plant occupies the verges of many miles of the M1 motorway, and speculate how horrified people would be if they knew what it was. Hemlock enjoys nitrogen, which it can absorb from the fumes emitted by lorries and cars, and from the run-off from agricultural land.
What about this poison business, though? Famously, Hemlock was the plant of choice for public executions in ancient Greece, and was used by Socrates to kill himself when he was condemned for corrupting the youth of Athens (by encouraging them to think for themselves) and offending the Gods (and the State). The lethal potion was called a pharmakon (the origin word of pharmacy and pharmaceuticals). According the account of the death of Socrates by Plato, this was a relatively gentle death: the executioner told Socrates to walk about his cell to speed the progress of the poison, which was experienced first as numbness in the feet, then in the legs. At this point, Socrates retired to his couch, where he continued to teach until respiratory paralysis set in. Socrates last words were said to be about making an offering to the god of medicine
‘Crito, we owe a cock to Asclepius. Make this offering to him, and do not forget‘.
All well and good except, as Peter Marren points out in ‘The Devil’s Garden‘, death by Hemlock poisoning is not like that at all: take this account by Nicander:
‘(Hemlock) assuredly looses disaster upon the head, brining the darkness of night: the eyes roll, and men roam the streets with tottering steps and crawling upon their hands; a terrible choking blocks the lower throat and narrow passage of the windpipe; the extremities grow cold, and in the limbs the stout arteries are contracted; for a short while the victim draws breath like one swooning, and his spirit beholds Hades’.
Scientists who have isolated the main ingredient in Hemlock (called coniine) agree that it causes paralysis of the nerves and muscles. It may be that Socrates fatal draught was laced with opiates or some other ingredient that made his death more gentle, or maybe Plato just wanted to leave his master with some dignity. The lesson here is ‘do not go munching on random plants’.
Why is Hemlock so poisonous? Clearly it’s been around for a lot longer than humans have, so it didn’t evolve to purposefully poison Greek philosophers. One explanation may be pest control – the plant is poisonous to many grazing animals. Conversely, the alkaloids in the poison are concentrated in the flower buds, and may be attractive to pollinators.
Interestingly, the leaves of this deadly poisonous plant were used in the mountainous regions of Georgia as food – it’s reported that the locals knew the plant was poisonous, and would treat it by washing in several changes of water before eating it. This practice has largely ceased since better food sources have become available.
Medicinally, Hemlock was used as a treatment for rabies – it was combined with the seeds of betony and fennel. As rabies is still 100 percent fatal once symptoms appear, we can assume that Hemlock was not successful. It was also used in a last desperate attempt to treat strychnine poisoning, and also as a treatment for gout – as this last complaint is intensely painful, I can imagine that people were ready to try anything, although as the roasted root was applied externally this was less risky than direct ingestion.
In the Victorian language of flowers, giving someone Hemlock meant ‘You’ll be the death of me’. I can imagine that receiving a bunch of mousy-smelling deadly poisonous flowers would probably have put paid to that particular relationship.
As one might expect of such a powerful plant, Hemlock is mentioned in accounts of witchcraft – it’s thought to be one of the ingredients of the ‘flying potion’ that enables witches to fly. The genus name ‘Conium’ means ‘to whirl’, which probably relates to the giddiness associated with ingesting the plant, but might also give a sensation of flying. It was used to reduce male potency, and was said to be used by Circe and Medea to poison their male enemies.
One species of moth has made a speciality of eating Hemlock leaves: the Hemlock Moth (Agonopterix alstromeriana). As Hemlock is now widespread not only in Europe, but also in the US and Australia, this little moth has been used as a biological control: it only eats Hemlock leaves, so this means that the caterpillars don’t transfer their voracious appetite to other related species. The caterpillar uses the toxins from the plant to defend itself from predators, who quickly learn to leave it alone. Interestingly, birds don’t seem to be affected by the toxins in the seeds of Hemlock, presumably so that they can spread the plant around.
Hemlock Moth (Agonopterix_alstromeriana,_Aberdovey,_North_Wales,_July_2006_(20191381660)
And finally, a tale from ‘Flora Britannica’ by Richard Mabey. Anne Pratt (1806-1893) was the botanist author of many books. In ‘Poisonous, Noxious, and Suspected Plants, of our Fields and Woods’ she tells a story of an eccentric lighthouse keeper who lived in Kent in the 1850s, and who made a bower out of Hemlock, in spite of its poisonous leaves and unpleasant scent:
‘A large bed of Hemlock grows there, and the man occupied in the charge of the Marine Telegraph at that station has availed himself of its abundance to deck with its stems and branches his little cave in the cliffs. This has a sloping entrance, and all about it he has planted the Hemlock, which attains there a great luxuriance, and is in summer six feet high, affording by its numerous branches a shelter alike from sun and shower. The owner of the cave, an intelligent man, has an eye for grace and beauty, and prizes the elegant foliage, taking care to preserve its verdure by cutting off the fruits as they appear; while the robustness given by an out-of-door life, by airs and sounds from the sea, have rendered his nervous system too strong to be injured by the odour. To him the faint smell gives no disgust, though he tells how a friend, and old coast-guardsman, who occasionally visits him, cautiously declines to subject himself to its influence and seats himself on some crag at a distance, where he may see its branches wave in safety’.
I rather fancy such a green bower myself, though maybe made out of hemp agrimony rather than Hemlock. But to each his own!
![By Ben Sale from UK ([1669] Common Emerald (Hemithea aestivaria)) [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons](https://i0.wp.com/bugwomanlondon.com/wp-content/uploads/2016/12/1669_common_emerald_hemithea_aestivaria_3639821862.jpg?ssl=1)
![By Gaudete [CC BY-SA 2.5 (http://creativecommons.org/licenses/by-sa/2.5)], via Wikimedia Commons](https://i0.wp.com/bugwomanlondon.com/wp-content/uploads/2016/12/privet_hawk-moth_sphinx_ligustri_02.jpg?ssl=1)
