Oenanthe crocata
Oenanthe crocata, hemlock water-dropwort (sometimes known as dead man's fingers) is a flowering plant in the carrot family, native to Europe, North Africa and western Asia. It grows in damp grassland and wet woodland, often along river and stream banks. All parts of the plant are extremely toxic and it has been known to cause human and livestock poisoning.
Distribution and status[edit]
The native distribution of hemlock water-dropwort is concentrated along the Atlantic seaboard of Europe, from the coast of the Netherlands south to Portugal and Spain, rapidly becoming rare inland. It is common again in Corsica and Sardinia but otherwise only sparsely distributed around the Mediterranean east to Syria and southwards to Morocco. It is perhaps most common in Britain and Ireland, where it is widespread throughout, even in inland locations.[15][16]
There are few records of it as an introduction outside its native range, although it has been reported from Argentina.[17]
In France, where it is known as "oenanthe jaune safran", it is considered unthreatened ("Least Concern", or LC), although in some départements it is rarer; for example, in Île-de-France and Picardy it is classified as Critically Endangered (CR).[18] In Britain, it is similarly listed as LC.[19]
Toxicity[edit]
The toxic principle in the plant is oenanthotoxin, a polyunsaturated higher alcohol that is a potent convulsant and works by blocking the γ-aminobutyric acid (GABA) system in the brain. The plant is very poisonous to humans and livestock and can cause death if poisoning is left untreated after ingestion. Symptoms in livestock include increased salivation, dilated pupils, respiratory distress, and convulsions.[2] Cattle poisoning from this plant occurs sporadically. For example, several cases were reported during the 1995 drought in the West Country, England. Due to the shortage of grass in the fields, the cattle were driven to graze by ditches where hemlock water-dropwort grew.[28]
Instances of poisoning in humans are rare, with only 13 cases reported in Britain between 1900 and 1978, mostly involving children. However, 70% of these were fatal.[11] Serious cases usually involved consumption of the roots, which were mistaken for wild parsnip.[28][29] Symptoms include nausea, vomiting, seizures, hallucinations, ataxia, haemorrhaging of the brain and collapse of the lungs.[30] Accidental splashing of some sap in the eye of a laboratory worker led to symptoms of poisoning that lasted 12 hours.[31] The Scottish botanist John Lightfoot, in his 'Flora Scotica' (1777) related the experience of the illustrator Georg Ehret, who found that "the smell, or effluvia only, rendered him so giddy that he was several times obliged to quit the room" until he opened the door and windows so that he could finish his work.[32] Oenanthotoxin is quite unstable, and boiling the roots both lessens the severity of the symptoms and prolongs the delay before they appear.[29]
Uses and in culture[edit]
Scientists at the University of Eastern Piedmont in Italy wrote that they had identified Oenanthe crocata as the plant responsible for producing the sardonic grin.[33][34] This plant is a possible candidate for the "sardonic herb", which was a neurotoxic plant referred to in ancient histories. It was purportedly used for the ritual killing of elderly people and criminals in Nuragic Sardinia. The subjects were intoxicated with the herb and then dropped from a high rock or beaten to death.[35][36]
The essential oils from the seeds of O. crocata have been shown to have moderate antibacterial effect against Enterococcus faecalis and Bacillus lentus.[37] The oils are also anti-inflammatory, antioxidant and anti-fungal (esp. against Cryptococcus neoformans), and they have been suggested for use in counteracting inflammatory diseases.[38] In the past, extracts from this plant have been used in medicine, for example as a treatment for epilepsy,[39] and in Ireland it was apparently commonly used in a poultice for treating skin disorders and even cancers.[40]