Conium

Poison hemlock redirects here. For other uses of "hemlock", see Hemlock.

Conium is a genus of two species of perennial herbaceous flowering plants in the family Apiaceae, native to Europe and the Mediterranean region (C. maculatum), and to southern Africa (C. chaerophylloides).

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By far the most familiar species is Conium maculatum (Hemlock or Poison Hemlock), the most common of several species of hemlock noted for their toxicity. It is a herbaceous biennial plant which grows between 1.5–2.5 m tall, with a smooth green stem, usually spotted or streaked with red or purple on the lower half of the stem. The leaves are finely divided and lacy, overall triangular in shape, up to 50 cm long and 40 cm broad. The flowers are small, white, clustered in umbels up to 10–15 cm across. The plant is often mistaken for fennel, parsley or wild carrot although the characteristic stem hairs of the wild carrots are missing. The Conium root is fleshy, white and often unbranched and can be mistaken for parsnip. When crushed, the leaves and root emit a rank, unpleasant odour often compared to that of parsnips.

  Conium contains the alkaloids coniine, N-methylconiine, conhydrine, pseudoconhydrine, g-coniceïne and atropine.

The most important and toxic of these is coniine. Coniine is a neurotoxin, which disrupts the workings of the peripheral nervous system and is toxic to people and all classes of livestock. Coniine causes death by blocking the neuromuscular junction in a manner similar to curare; this results in an ascending muscular paralysis with eventually paralysis of the respiratory muscles which results in death due to lack of oxygen to the heart and brain. Death can easily be prevented by artificial ventilation until the effects have worn off.

Conium maculatum has been introduced and naturalised in many other areas, including much of Asia, North America and Australia. Poison hemlock is often found on poorly drained soils, particularly near streams, ditches, and other surface water.

A useful trick to determine whether a plant is poison hemlock rather than fennel, which it resembles, is to crush some leaves and smell the result. Fennel smells like anise or liquorice, whereas the smell of poison hemlock is often described as mouse-like or musty.^{[citation needed]} Considering the high toxicity of poison hemlock, if the plant cannot be identified it must be discarded.

Conium is used as a food plant by the larvae of some Lepidoptera species including Silver-ground Carpet.

Poison hemlock flourishes in the spring, when most other forage is gone. All plant parts are poisonous but once the plant is dried, the poison is greatly reduced, however not gone completely. Hemlock is also known as "poison parsley" or "spotted parsley".

Poison hemlock is sometimes confused with water hemlocks in the related genus Cicuta, but are readily distinguished by the less finely divided leaves of the latter; the leaf veins of poison hemlock also run through the tips of the teeth, but those of the water hemlock run through the notches in between the teeth. The poison hemlock's root is long, white, and fleshy. It is unbranched and can usually be distinguished from the water hemlock's roots that are made up of several tubers.

Socrates

Main article: Trial of Socrates

In ancient Greece, hemlock was used to poison condemned prisoners. The most famous victim of hemlock poisoning is the philosopher Socrates. After being condemned to death for impiety in 399 BC, Socrates was given a potent solution of the hemlock plant. Plato described Socrates' death in the Phaedo ^[1]:

"The man … laid his hands on him and after a while examined his feet and legs, then pinched his foot hard and asked if he felt it. He said ‘No’; then after that, his thighs; and passing upwards in this way he showed us that he was growing cold and rigid. And then again he touched him and said that when it reached his heart, he would be gone. The chill had now reached the region about the groin, and uncovering his face, which had been covered, he said — and these were his last words — 'Crito, we owe a cock to Asclepius. Pay it and do not neglect it.' 'That,' said Crito, 'shall be done; but see if you have anything else to say.' To this question he made no reply, but after a little while he moved; the attendant uncovered him; his eyes were fixed. And Crito when he saw it, closed his mouth and eyes."^[2]

Although many have questioned whether this is a factual account, careful attention to Plato's words, modern and ancient medicine, and other ancient Greek sources point to the above account being consistent with Conium poisoning.^[3]

Sometimes the characteristic red spots found on the stem and branches are referred to as "the blood of Socrates" in reference to his death.

Medicinal uses

Poison hemlock has been used as a sedative and for its antispasmodic properties. It was also used by Greek and Persian physicians for a variety of problems, such as arthritis. However, it wasn't always effective as the difference between a therapeutic and a toxic amount is very slight. Overdoses can produce paralysis and loss of speech being followed by depression of the respiratory function and then death.

References and external links

1. ^ http://perseus.mpiwg-berlin.mpg.de/cgi-bin/ptext?lookup=Plat.+Phaedo+117e
2. ^ Plato, Phaedo 117e–118a, trans. Loeb Classical Library, Harvard University Press, Cambridge, Mass., 1990 edition, pp. 401–3.
3. ^ Bloch, Enid (March 2001). "Hemlock Poisoning and the Death of Socrates: Did Plato Tell the Truth?". Journal of the International Plato Society (1). A version of this article was also printed in Thomas C. Brickhouse (Editor), Nicholas D. Smith (Editor) (2001). The Trial and Execution of Socrates: Sources and Controversies. ISBN 978-0195119800. 

• Germplasm Resources Information Network: Conium
• Flora Europaea: Conium