Oenanthe crocata

Oenanthe crocata
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Asterids
Order:	Apiales
Family:	Apiaceae
Genus:	Oenanthe
Species:	O. crocata
Binomial name
Oenanthe crocata L.

Oenanthe crocata, the hemlock water-dropwort, also known as dead man's fingers,^[1] is a flowering plant in the carrot family, Apiaceae, native to the British Isles, Western Europe and the Iberian Peninsula. All parts of the plant are extremely toxic and have been implicated in several cases of livestock poisoning. The toxic leaves and stems look like parsley; the highly toxic roots look and smell like parsnips.^[1]

Description[]

Hemlock water-dropwort is a robust hairless perennial growing up to 150 cm tall and with hollow, cylindrical grooved stems up to 1 cm across. The 3-4 times pinnate leaves are triangular, with oval toothed leaflets that are basally tapered to the stalk^[2] and a characteristically deceptive smell of parsley or celery.^[3]

This species usually flowers June – July. The white, mostly hermaphroditic flowers have unequal petals and measure 2mm in width.^[4] They are borne in many-rayed umbels that are almost spherical and measure 5 – 10 cm across. The numerous bracts and bracteoles soon fall off during flowering.^[5] The cylindrical fruits are 4 – 6 mm long, with styles measuring 2 mm in length. The roots are pale yellow and composed of 5 or more fleshy tubers that exude yellowish fluid when cut that stains the skin.

Distribution and habitat[]

Hemlock water-dropwort is native to the British Isles, although only common locally in the south and west and rarer or absent elsewhere. The native range extends from Britain, Belgium and Netherlands down to southwestern Europe, the western Mediterranean and North Africa.^[6] It grows in shallow freshwater in streams, marshes, lakes, ponds, canals, wet woodland and on riverbanks as well as in rocky coastal streams.^[3] The plant is usually a calcifuge, and as a lowland species it nearly always occurs below 300 m.^[3]

Toxicity[]

The toxic principle in the plant is oenanthotoxin, a polyunsaturated higher alcohol that is a potent convulsant and resembles cicutoxin, the toxic constituent in hemlock. The plant is very poisonous to humans and livestock and can cause imminent death if poisoning is left untreated after ingestion. Symptoms in livestock include increased salivation, dilated pupils, respiratory distress, and convulsions. 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.^[7] More occasional instances of human poisoning have also been reported, in which the plant roots consumed were mistaken for wild parsnip and the leaves for wild celery.^[7][8] Symptoms in humans include nausea, vomiting, seizures, hallucinations, ataxia, and respiratory distress.^[9]

The roots are the most toxic part of the plant, with toxin concentrations being highest in winter and spring.^[9] Boiling the roots seems to both lessen the severity of the symptoms and prolong the delay after which they appear following ingestion.^[8]

Uses and in culture[]

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.^[10][11] 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.^[12][13]

The essential oils from the seeds of O. crocata have been shown to have moderate antibacterial effect against Streptococcus faecalis and .^[14] 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.^[15]

Similar species[]

The hemlock water-dropwort shares a genus with many other superficially similar European water-dropworts, all of which are poisonous but not deadly.

References[]