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Conium maculatum, poison hemlock


Though somewhat similar in appearance to other plants with 'hemlock' in their common names, Conium maculatum is distinguished by its action of killing from the outside in as numbness of the extremities slowly becomes paralysis of the lungs. It has no effect on the brain.

'Poisonous Plants 1-2-1' video

This short video summarising the story of poison hemlock is just one of a series.


Umbelliferae (Apiaceae is the modern name for this family.)

Meaning of the Name

Conium maculatum, poison hemlock

Conium maculatum, poison hemlock

From the Greek ‘kōneion’ meaning ‘hemlock’ which doesn’t move things very far forward as Geoffrey Grigson says that there is no definition of ‘hemlock’ and the word, nor any like it, does not appear in any language other than English. ‘Hemlock’ is said to come from the Old English ‘hymlice’ or ‘hymlic’ and Stephen Pollington, in ‘Leechcraft’, suggests that this may be connected to ‘hymele’ the Old English for ‘hop plant’. The ‘lic’ or ‘lice’ ending in Old English is often translated as ‘like’. But there is no obvious connection between the Conium and the Humulus in appearance or natural habit.
‘Hym’ in Old English is simply ‘him’ but it seems unlikely that ‘hymlic’ was simply ‘him like’.
‘Spotted’ or ‘speckled’. Plants called ‘maculatum’ are usually said to have grown under the cross and been speckled with Christ’s blood. With the C. maculatum, this folklore is reinforced by the fact that the speckles do not appear until the spring and may be said to appear at Easter.

Common Names and Synonyms

poison hemlock, woomlicks beaver poison, poison parsley, spotted hemlock kex, badman’s oatmeal, bunk, break-your-mother’s-heart, hever, caise, cartwheel, devil’s flower, gipsy flower, curtains, hare’s parsley, lady’s lace, nosebleed, pickpocket, scably hands, stink flower, devil’s blossom, honiton lace.

How Poisonous, How Harmful?

Conium maculatum, poison hemlock

Five alkaloids are present. Coniine is the most important. Conhydrine, pseudoconhydrine, methyl-coniine and ethyl-piperidine are the other four.

It is a violent emetic and convulsive, causing paralysis of the central and peripheral nervous system. Death is usually the result of respiratory failure. In Plato’s ‘Phaedo’ the fictionalised account of Socrates’ death there is no mention of nausea and vomiting. It may be that whilst the plant material is emetic juice obtained from squeezing the stalks does not have this effect.

Being a member of the same family as carrot and fennel, there have been instances of its being mistaken for an edible plant though its mouse-like smell is, generally, a deterrent to ingestion.


Conium maculatum, poison hemlock

On 1st April 2010, a 55-year old woman in Washington state, USA, died after, it is believed, putting Conium maculatum in a salad, by mistake. Her death certificate apparently states “Probable intoxication following ingestion of toxic substance.” Toxicology reports were not available when the story was reported as part of the following incident.

Also in April 2010, a man, also in Washington state, USA, pulled up a poison hemlock plant in his own garden, thinking it was a leftover from his previous year's carrot crop. He used it as an ingredient of a batch of pickled vegetables and, within fifteen minutes of eating some, became aware that his eye movements had slowed. He was on his way to visit friends and had begun shaking by the time he arrived. The friends took him to hospital where he made a full recovery.

Between 1972 and 1990 there were 17 cases in Italy of hemlock poisoning after eating wild birds, a common practice. The birds feed on hemlock but are unaffected by it. The toxins remain active, even in some of the cases, after the meat had been frozen for storage. One person died from respiratory failure after 36 hours and another three died of kidney failure.

Conium maculatum, poison hemlock

An inquest, in October 2006, heard how a biochemist used hemlock to commit suicide in June 2005. Wayne Calderwood collected hemlock from around his allotment and crushed it up in alcohol. Post mortem examination showed that his throat had constricted by 70% and death resulted from suffocation.

A 19th century American doctor, Dr. J. H. Bennett, reported the case of someone who was said to have eaten a large quantity of hemlock plant, mistaking it for parsley. He soon lost the feeling in his legs but it was over three hours before he died of respiratory failure. He was alert throughout. There is no mention of the vomiting which ingestion of the plant itself is, generally, said to cause.

A man, probably in his 60s, remembered that, when he was five, his nine year old cousin died from hemlock poisoning after eating the plant in mistake for something else.

In the state of Victoria in Australia a 3-year old boy died, in 1994, after ingesting 'hemlock' found in the back garden of a rural property. Three other children spat the leaves out when they found the taste unpleasant.

The 2002 annual meeting of the North American Congress of Clinical Toxicology heard a case report of two 13-year old girls who ate Conium maculatum thinking it was parsley. One died. The plant was positively identified from material recovered from the stomach of the deceased.


One of the clearest ways to identify Conium maculatum is from the 'mousey' smell which is especially strong on a warm day. Sadly, it is not, yet, possible to convey smell on a webpage but these photos may help to separate poison hemlock from Anthriscus sylvestris, cow parsley.

Conium maculatum leaf

Conium maculatum leaf

Anthriscus sylvestris leaf

Anthriscus sylvestris leaf












Other than being slightly more shiny and a brighter green colour, there is little to distinguish between the leaves and, certainly, if only one of the plants is available identification would be difficult.

The stems and stalks are much more helpful.

Conium maculatum stalk

Conium maculatum stalk

Anthriscus sylvestris stalk

Anthriscus sylvestris stalk











Note that, on a young plant, the purple spots may not have developed.

Folklore and Facts

Conium maculatum, poison hemlock

The speckled stalks of poison hemlock

Conium maculatum is another plant which was said to have been speckled by Christ's blood as it grew under the cross. This may be because the speckles are not visible on the young plant and could be thought to appear at Easter to coincide with the crucifixion.

It is generally agreed that it was poison hemlock which killed Socrates though you do see accounts claiming it was water hemlock, Cicuta virosa. The symptoms described in the 'Phaedo' are those of poison hemlock that is the slow numbing, first of the limbs but then the rest of the body with full consciousness being retained throughout.

It must be said that Phaedo is a fictional character, created by Plato, to describe the death of Socrates so the account may include literary licence.

Even if the agent of his death is accepted, the circumstances surrounding it are unknown. Some sources insist on referring to Socrates' suicide although it is clear that he was under sentence of death. What is less clear is whether poison was the normal means of execution or whether, as a gentleman, Socrates was given the chance to avoid public execution by taking poison and whether he had a choice of which poison to take.

Conium maculatum, poison hemlock

Though the evidence is incomplete, it seems that quick acting poisons were known to the Ancient Greeks. The choice of a slow killer like poison hemlock seems odd unless Socrates, as a philosopher, wanted to know what it felt like to be aware of his own impending death.

For some time, like many others, I had accepted that Aconitum lycoctonum, wolfsbane, was the poison used on Ceos (sometimes called Keos or Kea) to dispose of the elderly. I'm grateful to Gary Corby for pointing out that Strabo, the Greek geographer, is clear that poison hemlock was the substance used. The question of whether this was compulsory or voluntary euthanasia would, however, seem to be open. Strabo writes that the law 'ordered those who were over sixty years of age to drink hemlock' but quotes Menander as writing 'the law of the Ceians is good, that he who is unable to live well should not live wretchedly' which might be taken to mean that the law allowed for euthanasia rather than requiring it. Corby notes that in Athens suicide was considered a crime so, perhaps, it required a specific law, on Ceos, to allow it.

Poison hemlock is, generally, a key component of the 'soporific sponge', used to achieve anaesthesia for the performance of surgery. Its precise origin is impossible to determine but one of the first published accounts is found in the 'Antidotarium' of Nicolaus Salernitanus, Nicholas of Salerno, printed in 1470 but which would have to have been written in the 12th century if it is the work of Nicholas. In this recipe, the normally quoted formula of opium, henbane and hemlock is augmented with mulberry juice, mandrake, ivy and lettuce.

A sponge would be soaked in the juice of these plants and then dried to be held in stock until required. Wetting the sponge and placing it over the patient's nose and mouth resulted in the inhalation of the narcotic fumes. It is said that sleep lasting up to 96 hours could be achieved so that the body had the opportunity to recover from the trauma of surgery as well as the patient being insensible during the procedure. 


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Introduction to the A to Z section
Abrus precatorius, rosary pea
Aconitum lycoctonum, wolfsbane
Aconitum napellus, monkshood
Actaea racemosa, black cohosh
Actaea spicata, baneberry
Aesculus hippocastanum, horse chestnut
Amanita muscaria, fly agaric
Aquilegia atrata, columbine
Aristolochia clematitis, birthwort
Artemisia absinthium, wormwood
Arum italicum, Italian cuckoopint
Arum maculatum, cuckoopint
Aspergillus fumigatus
Atropa belladonna, deadly nightshade
Brugmansia suaveolens, angel's trumpet
Bryonia dioica, bryony
Buxus sempervirens, common box
Camellia sinensis, tea
Cannabis sativa, marijuana
Catha edulis, khat
Chelidonium majus, greater celandine
Cimicifuga racemosa, black cohosh
Claviceps purpurea, ergot
Clematis vitalba, old man's beard
Colchicum autumnale, naked ladies
Conium maculatum, poison hemlock
Convallaria majalis, lily of the valley
Cynoglossum officinale, hound’s tongue
Daphne mezereon, spurge olive
Datura stramonium, thorn apple, jimsonweed
Datura suaveolens, angel's trumpet
Delphinium, larkspur
Digitalis spp., foxglove
Dracunculus vulgaris, dragon arum
Echium vulgare, viper’s bugloss
Eranthis hyemalis, winter aconite
Erythroxylum coca, cocaine
Euonymus europaeus, spindle tree
Euphorbia x martinii, red spurge
Euphorbia pulcherrima, poinsettia
Fritillaria spp., fritillary
Galanthus nivalis, snowdrop
Hedera helix, common ivy
Helleborus spp., hellebore
Heracleum mantegazzianum, giant hogweed
Hyacinthoides non-scripta, bluebell
Hyoscyamus niger, black henbane
Ilex aquifolium, holly
Jacobaea vulgaris, ragwort
Juniperus communis, common juniper
Laburnum anagyroides, laburnum
Lactuca serriola, prickly lettuce
Leucojum aestivum, snowflake
Lithospermum officinale, gromwell
Lolium temulentum, darnel
Malus 'John Downie', crab apple
Mandragora officinarum, mandrake
Mercurialis perennis, dog’s mercury
Narcissus, daffodil
Nepeta faassenii, catmint
Nerium oleander, oleander
Nicotiana sylvestris, tobacco
Oenanthe crocata, hemlock water dropwort
Papaver somniferum, opium poppy
Pastinaca sativa, parsnip
Polygonatum odoratum, angular Solomon's seal
Prunus laurocerasus, cherry laurel
Pulsatilla vulgaris, pasque flower
Ranunculus acris, meadow buttercup
Rheum x hybridum, rhubarb
Rhododendron spp.
Rhus radicans, poison ivy
Ricinus communis, castor oil plant
Rosmarinus officinalis, rosemary
Rumex obtusifolius, broad-leaved dock
Ruta graveolens, rue
Salix alba, white willow
Salvia divinorum, sage
Scutellaria laterifolia, Virginian skullcap
Senecio jacobaea, ragwort
Solanum dulcamara, woody nightshade
Solanum melongena, aubergine
Strychnos nux-vomica, poison nut
Symphoricarpos albus, snowberry
Symphytum spp., comfrey
Taxus baccata, yew
Toxicodendron radicans, poison ivy
Thevetia peruviana, yellow oleander
Urtica dioica, stinging nettle
Veratrum album, white hellebore
Verbascum olympicum, Greek mullein
Vinca major, greater periwinkle
Viscum album, mistletoe
Vitex agnus-castus, chaste tree