Cicuta
Encyclopedia
Cicuta, commonly known as water hemlock, is a small genus
of four species of highly poisonous plants in the family Apiaceae
. They are perennial
herbaceous
plants which grow up to 2.5 metres (8.2 ft) tall, having distinctive small green or white flowers arranged in an umbrella shape (umbel
). Plants in this genus may also be referred to as cowbane or poison parsnip. Cicuta is native to temperate
regions of the Northern Hemisphere
, mainly North America
and Europe
, typically growing in wet meadows, along streambanks and other wet and marshy areas. These plants bear a close resemblance to other members in the family Apiaceae and may be confused with a number of other edible and poisonous plants. The common name hemlock may also be confused with poison hemlock (Conium maculatum).
Water hemlock is considered one of North America's most toxic plants being highly poisonous to humans. Three members of the genus contain a toxin
named cicutoxin
which causes central nervous system
stimulatory effects including seizure
s following ingestion. Medical treatment of poisoning may include the use of activated charcoal to decrease gastrointestinal absorption of the toxic principle along with supportive care including anticonvulsant
drugs such as a benzodiazepine
. High doses of anticonvulsant medicine are often required to halt seizure activity and further medical care including intubation
and mechanical ventilation
may be required.
Cicuta spp. are perennial plants that are all similar in morphology
, growing up to a maximum of 2.5 metres (8.2 ft) in height. The stem of the plant is branching, erect, smooth and hollow (except for partitions at the junction of the leaves and stem), sometimes being purple-striped, or mottled (typically only C. maculata has the purple stripes or spots). Attached to the base of the stem is a tuberous root with thickened rootstock
s. The rootstocks are multichambered and contain a yellowish oily liquid which turns reddish brown on exposure to air and emits a characteristic smell of raw parsnip. The alternate
leaves
are 2 or 3 pinnate
ly compound and may reach 30 centimetres (11.8 in) to 90 centimetres (35.4 in) in length. The leaflets are lanceolate, serrate, 5 centimetres (2 in) to 10 centimetres (3.9 in) in length, and sharply toothed. The plant flowers in spring or early summer; the flowers are small with green or white petals clustered in an umbrella shape (umbel
) characteristic to this family; the umbel measures 5 centimetres (2 in) to 10 centimetres (3.9 in) across. The plants produce a cylindrical fruit which is 4 millimetre (0.15748031496063 in) to 6 millimetre (0.236220472440945 in) in length. The plant is spread primarily by seeds which are produced in large numbers and are small in size.
family
which is in the order Apiales
. The Apiaceae family is also known as Umbelliferae and both of these family names are permitted to be used by the International Code of Botanical Nomenclature. In Europe, Cicuta was not distinguished from the similar genus Conium
before the year 1500. The first mention of the genus in the United States
was in the eighteenth century. Carl Linnaeus formally described three species in 1753. The type species
is C. virosa. The genus is now recognized to comprise four species:
Other species names such as Cicuta bolanderi, Cicuta californica, and Cicuta curtissii are older names now recognized to be varieties of the widespread, morphologically
variable Cicuta maculata. Cicuta maculata is now recognized to have four varieties: var. maculata, var. augustifolia, var. victorinii, and var. bolanderi. Phylogenetic
analysis using the sequences
of nuclear ribosomal DNA
internal transcribed spacer
(ITS) loci was not conclusive but seems to show that C. bulbifera and C. virosa are monophyletic, while C. douglasii may not be. It was also suggested a specimen from California may warrant recognition as a distinct species. Other common names for the genus in general include poison parsnip, beaver poison, wild carrot, wild parsnip, and false parsley.
), wild carrot (Daucus carota), watercress (Nasturtium
spp.), wild ginseng (Panax quinquefolius), wild parsnip (Pastinaca sativa), and water parsnip (Berula
spp.). One of the more common misidentifications is between water hemlock and water parsnip; both have clusters of small white flowers shaped like umbrellas, and both have the same habitat near the shore line of lakes and rivers. Differences between water parsnip and water hemlock include the water parsnip having leaves only once compound while the water hemlock has leaves which are two or three times compound. Water hemlock also has a large swelling at the stem base which water parsnip lacks. Additionally, water hemlock has bract
s at the base of each small flower cluster, not at the base of the main flower head, while water parsnip has both bracts at the base of flowers and also at the main flower head.
Other plants that look similar to Cicuta spp. but are not edible are the yarrow, (Achillea millefolium, also commonly known as common yarrow, gordaldo, nosebleed plant, old man's pepper, sanguinary, milfoil, soldier's woundwort, thousand-leaf, and thousand-seal), cow Parsnip (Heracleum lanatum, also known as Heracleum maxinium, Indian celery or pushki) or hogweed (Heracleum sphondylium). Features which differentiate them include the yarrow having feathery looking leaves which are pinnately
separated into small narrow segments, while cow parsnip and hogweed have large, broad leaves, and an unpleasant odor.
Additionally, there can be confusion between the various water hemlock species and poison hemlock (Conium maculatum) as the common name hemlock is applied to both Cicuta and Conium maculatum. Both are poisonous and can be differentiated by differences in their root structure. Water hemlock has a branched root systems with tubules, while poison hemlock has a single tap root. Another reliable method to identify water hemlock is to examine the leaf veins. Water Hemlock is unique in the Apiaceae family in that it has leaf veins which terminate in the notches between the leaf tips, rather than extend to the tip of the leaf, as is found in the leaf structure of other members of this family.
has the most widespread distribution occurring across the majority of North America. Cicuta bulbifera also has a relatively large distribution, found throughout Northern North America. Cicuta douglasii is found in the northwest corner of North America, while Cicuta virosa
is only found in central Europe
and in the far north of North America.
All members of Cicuta except C. bulbifera contain high levels of the poisonous principle cicutoxin
, an unsaturated
aliphatic
alcohol
that is structurally
closely related to the toxin oenanthotoxin
found in the plant hemlock water dropwort
. Cicutoxin is present at all stages of growth and in all parts of the plant, but is most concentrated in the roots which appear to be the most toxic in the early spring. Its primary toxic effect is to act as a stimulant in the central nervous system
. It is a non-competitive gamma-aminobutyric acid
(GABA) receptor antagonist
. Cicutoxin acts on the GABAA receptor causing a block of the chloride channel
which results in neuronal depolarization. In the presence of cicutoxin this depolarization continues unabated causing cell overactivity. The hyperactivity in brain cells results in seizures. Cicutoxin is highly poisonous and water hemlock is considered one of North America's most toxic plants. Ingestion of Cicuta can be fatal in humans and there are reports in the medical literature of severe poisoning and death as early as 1670. A number of people have also died following ingestion of the plant in the 20th and 21st century.
The in mice administered cicutoxin by intraperitoneal injection
is 48.3 mg per kg body weight
(mg/kg); this compares with 5.9 mg/kg for mice given potassium cyanide
by intraperitoneal injection
, while the LD50 for arsenic
via intraperitoneal injection in mice is 46.2 mg/kg. The exact toxic dose of plant material in humans is unknown; it is thought ingestion of water hemlock in any quantity can result in poisoning and very small amounts may lead to death. Poisoning has been reported following children blowing whistles made from the hollow stem of water hemlock plants. Intoxication has also been reported following skin contact with the plant; a case was reported where a family of five people rubbed the plant onto the skin and were poisoned, with two children dying. Livestock
have long been the worst affected, leading to the common name "cowbane". Poisoning in livestock is common and typically occurs following ingestion of roots of the plant. In the spring when the ground is soft, grazing animals tend to pull the entire plant out of the ground ingesting both the foiliage and the roots. Roots exposed by ploughing can also be the source of livestock poisonings. Ingestion of plant material may cause death in the animal in as little as 15 minutes.
, vomiting
, abdominal pain
, tremor
s, confusion
, weakness, dizziness
, and drowsiness; although the rapid onset of seizure activity may be the first sign presenting following poisoning. Seizures are usually described as clonic or tonic–clonic. Complications of ongoing seizure activity include increased body temperature
, decreases in the pH of the blood
(metabolic acidosis), swelling in the brain
, blood coagulation disorders
, muscle breakdown
(rhabdomyolysis), and kidney failure. Additional neurological symptoms may include hallucinations, delirium
, tingling, pricking, or numbness of a person's skin
, dilated pupils
, and coma
. Cardiovascular symptoms include alternating slow
or fast heart rate
and alternating low
and high blood pressure
. Other cardiac effects may include ECG abnormalities such as widening of the PR interval
, supraventricular tachycardia
, and ventricular fibrillation
. Symptoms of excess salivation, wheezing, respiratory distress
, and absence of breathing
have also been reported.
Deaths usually occur from respiratory failure
or ventricular fibrillation
secondary to ongoing seizure activity; fatalities have occurred within a few hours of ingestion. Poisoned people who recover usually regain consciousness and seizures cease within 24 to 48 hours of poisoning, although seizures may persist for up to 96 hours. There are occasional long-term effects such as retrograde amnesia
of the events leading to intoxication and the intoxication itself. Other ongoing mild effects may include restlessness
, muscle weakness
, twitching
, and anxiety
. Complete resolution of symptoms may take a number of days or, in some cases, these ongoing symptoms may persist for months after poisoning.
, and mass spectrometry
have been used to detect cicutoxin but these tests are not performed routinely in hospital laboratories
. If a sample of the plant ingested has been retained, diagnosis can be confirmed by having the plant identified by a botanist.
Initial treatment of poisoning may include gastrointestinal decontamination with activated charcoal. Decontamination is typically only performed if a potentially toxic amount of plant matter has been ingested up to one hour previously and the patient has an normal intact airway
or has been intubated
. There is no specific antidote for water hemlock poisoning and treatment mainly consists of supportive care. Treatment may include control of seizure
s with the administration of a benzodiazepine
s such as lorazepam
or diazepam
, or if seizures are refractory to this treatment, a barbiturate
such as phenobarbital
is administered. The anticonvulsant
phenytoin
is not recommended as it has not been shown to be effective for seizure control following water hemlock poisoning. Treatment with high doses of benzodiazepines or barbiturates may cause respiratory depression and respiratory support including intubation
and mechanical ventilation
is required in these patients. Continuous electroencephalography
monitoring is recommended in symptomatic patients.
Further treatment for complications of metabolic acidosis
, rhabdomyolysis
, hyperthermia
, or low blood pressure may be required. Metabolic acidosis is treated by administering sodium bicarbonate
. Low blood pressure is usually treated with intravenous fluid replacement
, but the administration of dopamine
or norepinephrine
may be required to restore blood pressure. The management of rhabdomyolysis includes ensuring adequate hydration and urinary alkalinization; a complication of rhabdomyolysis is acute renal failure which may require management with hemodialysis
. However, hemodialysis, hemoperfusion
or other extracorporeal
techniques do remove cicutoxin from the blood and are therefore not useful in enhancing elimination.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of four species of highly poisonous plants in the family Apiaceae
Apiaceae
The Apiaceae , commonly known as carrot or parsley family, is a group of mostly aromatic plants with hollow stems. The family is large, with more than 3,700 species spread across 434 genera, it is the sixteenth largest family of flowering plants...
. They are perennial
Perennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...
herbaceous
Herbaceous
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...
plants which grow up to 2.5 metres (8.2 ft) tall, having distinctive small green or white flowers arranged in an umbrella shape (umbel
Umbel
An umbel is an inflorescence which consists of a number of short flower stalks which are equal in length and spread from a common point, somewhat like umbrella ribs....
). Plants in this genus may also be referred to as cowbane or poison parsnip. Cicuta is native to temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
regions of the Northern Hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
, mainly North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
and Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, typically growing in wet meadows, along streambanks and other wet and marshy areas. These plants bear a close resemblance to other members in the family Apiaceae and may be confused with a number of other edible and poisonous plants. The common name hemlock may also be confused with poison hemlock (Conium maculatum).
Water hemlock is considered one of North America's most toxic plants being highly poisonous to humans. Three members of the genus contain a toxin
Toxin
A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
named cicutoxin
Cicutoxin
Cicutoxin is a poisonous polyyne and alcohol found in various plants, most notably water hemlock . It is structurally related to the oenanthotoxin of hemlock water dropwort....
which causes central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
stimulatory effects including seizure
Seizure
An epileptic seizure, occasionally referred to as a fit, is defined as a transient symptom of "abnormal excessive or synchronous neuronal activity in the brain". The outward effect can be as dramatic as a wild thrashing movement or as mild as a brief loss of awareness...
s following ingestion. Medical treatment of poisoning may include the use of activated charcoal to decrease gastrointestinal absorption of the toxic principle along with supportive care including anticonvulsant
Anticonvulsant
The anticonvulsants are a diverse group of pharmaceuticals used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of bipolar disorder, since many seem to act as mood stabilizers, and in the treatment of neuropathic pain. The goal of an...
drugs such as a benzodiazepine
Benzodiazepine
A benzodiazepine is a psychoactive drug whose core chemical structure is the fusion of a benzene ring and a diazepine ring...
. High doses of anticonvulsant medicine are often required to halt seizure activity and further medical care including intubation
Intubation
Tracheal intubation, usually simply referred to as intubation, is the placement of a flexible plastic or rubber tube into the trachea to maintain an open airway or to serve as a conduit through which to administer certain drugs...
and mechanical ventilation
Mechanical ventilation
In medicine, mechanical ventilation is a method to mechanically assist or replace spontaneous breathing. This may involve a machine called a ventilator or the breathing may be assisted by a physician, respiratory therapist or other suitable person compressing a bag or set of bellows...
may be required.
Description
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
, growing up to a maximum of 2.5 metres (8.2 ft) in height. The stem of the plant is branching, erect, smooth and hollow (except for partitions at the junction of the leaves and stem), sometimes being purple-striped, or mottled (typically only C. maculata has the purple stripes or spots). Attached to the base of the stem is a tuberous root with thickened rootstock
Rootstock
A rootstock is a plant, and sometimes just the stump, which already has an established, healthy root system, used for grafting a cutting or budding from another plant. The tree part being grafted onto the rootstock is usually called the scion...
s. The rootstocks are multichambered and contain a yellowish oily liquid which turns reddish brown on exposure to air and emits a characteristic smell of raw parsnip. The alternate
Phyllotaxis
In botany, phyllotaxis or phyllotaxy is the arrangement of leaves on a plant stem .- Pattern structure :...
leaves
Leaves
-History:Vocalist Arnar Gudjonsson was formerly the guitarist with Mower, and he was joined by Hallur Hallsson , Arnar Ólafsson , Bjarni Grímsson , and Andri Ásgrímsson . Late in 2001 they played with Emiliana Torrini and drew early praise from the New York Times...
are 2 or 3 pinnate
Pinnate
Pinnate is a term used to describe feather-like or multi-divided features arising from both sides of a common axis in plant or animal structures, and comes from the Latin word pinna meaning "feather", "wing", or "fin". A similar term is pectinate, which refers to a comb-like arrangement of parts...
ly compound and may reach 30 centimetres (11.8 in) to 90 centimetres (35.4 in) in length. The leaflets are lanceolate, serrate, 5 centimetres (2 in) to 10 centimetres (3.9 in) in length, and sharply toothed. The plant flowers in spring or early summer; the flowers are small with green or white petals clustered in an umbrella shape (umbel
Umbel
An umbel is an inflorescence which consists of a number of short flower stalks which are equal in length and spread from a common point, somewhat like umbrella ribs....
) characteristic to this family; the umbel measures 5 centimetres (2 in) to 10 centimetres (3.9 in) across. The plants produce a cylindrical fruit which is 4 millimetre (0.15748031496063 in) to 6 millimetre (0.236220472440945 in) in length. The plant is spread primarily by seeds which are produced in large numbers and are small in size.
Taxonomy
The Cicuta genus is one of many genera in the ApiaceaeApiaceae
The Apiaceae , commonly known as carrot or parsley family, is a group of mostly aromatic plants with hollow stems. The family is large, with more than 3,700 species spread across 434 genera, it is the sixteenth largest family of flowering plants...
family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
which is in the order Apiales
Apiales
The Apiales are an order of flowering plants. The families given at right are those recognized in the APG III system. This is typical of the newer classifications, though there is some slight variation, and in particular the Torriceliaceae may be divided...
. The Apiaceae family is also known as Umbelliferae and both of these family names are permitted to be used by the International Code of Botanical Nomenclature. In Europe, Cicuta was not distinguished from the similar genus Conium
Conium
Conium is a genus of two species of highly poisonous perennial herbaceous flowering plants in the family Apiaceae, native to Europe and the Mediterranean region as Conium maculatum, and to southern Africa as Conium chaerophylloides....
before the year 1500. The first mention of the genus in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
was in the eighteenth century. Carl Linnaeus formally described three species in 1753. The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
is C. virosa. The genus is now recognized to comprise four species:
| Species Name | Common Name |
|---|---|
| Cicuta bulbifera L. Carolus Linnaeus Carl Linnaeus , also known after his ennoblement as , was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology... |
bulblet-bearing water hemlock, bulbous water hemlock |
| Cicuta douglasii (DC.) Coult. Thomas Coulter Thomas Coulter , of Dundalk, was an Irish physician, botanist, and explorer. He was a member of the Royal Irish Academy, and a fellow of Trinity College, Dublin, where he founded the college's herbarium.... & Rose Joseph Nelson Rose Joseph Nelson Rose was an American botanist. He was born in Union County, Indiana. His father died serving during the Civil War when Joseph Rose was a young boy. He later graduated from high school in Liberty, Indiana.... |
Douglas water hemlock, western water hemlock |
| Cicuta maculata Cicuta maculata Cicuta maculata is a species of flowering plant in the carrot family known by several common names, including spotted water hemlock, spotted parsley, spotted cowbane, and the suicide root by the Iroquois. It is native to nearly all of North America, from northern Canada to southern Mexico... L. Carolus Linnaeus Carl Linnaeus , also known after his ennoblement as , was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology... |
spotted cowbane, spotted parsley, spotted water hemlock |
| Cicuta virosa Cicuta virosa Cicuta virosa is a species of Cicuta, native to northern and central Europe, northern Asia and northwestern North America. It is a perennial herbaceous plant which grows up to 1–2 m tall. The stems are smooth, branching, swollen at the base, purple-striped, and hollow except for partitions at the... L. Carolus Linnaeus Carl Linnaeus , also known after his ennoblement as , was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology... |
cowbane, Mackenzie’s water hemlock, northern water hemlock |
Other species names such as Cicuta bolanderi, Cicuta californica, and Cicuta curtissii are older names now recognized to be varieties of the widespread, morphologically
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
variable Cicuta maculata. Cicuta maculata is now recognized to have four varieties: var. maculata, var. augustifolia, var. victorinii, and var. bolanderi. Phylogenetic
Phylogenetics
In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...
analysis using the sequences
Primary structure
The primary structure of peptides and proteins refers to the linear sequence of its amino acid structural units. The term "primary structure" was first coined by Linderstrøm-Lang in 1951...
of nuclear ribosomal DNA
Ribosomal DNA
Ribosomal DNA codes for ribosomal RNA. The ribosome is an intracellular macromolecule that produces proteins or polypeptide chains. The ribosome itself consists of a composite of proteins and RNA. As shown in the figure, rDNA consists of a tandem repeat of a unit segment, an operon, composed of...
internal transcribed spacer
Internal transcribed spacer
ITS refers to a piece of non-functional RNA situated between structural ribosomal RNAs on a common precursor transcript. Read from 5' to 3', this polycistronic rRNA precursor transcript contains the 5' external transcribed sequence , 18S rRNA, ITS1, 5.8S rRNA, ITS2, 28S rRNA and finally the 3'ETS...
(ITS) loci was not conclusive but seems to show that C. bulbifera and C. virosa are monophyletic, while C. douglasii may not be. It was also suggested a specimen from California may warrant recognition as a distinct species. Other common names for the genus in general include poison parsnip, beaver poison, wild carrot, wild parsnip, and false parsley.
Similar species
Members of the family Apiaceae bear close resemblance to each other, and have many characteristics in common. Cicuta spp. are often mistaken for edible plants such as sweet flag (Acorus calamus), kvanne (Angelica archangelica), wild celery (Apium graveolens), pignut (Conopodium majusConopodium majus
Conopodium majus is a small perennial herb, whose underground part resembles a chestnut and is sometimes eaten as a wild or cultivated root vegetable....
), wild carrot (Daucus carota), watercress (Nasturtium
Nasturtium (genus)
Nasturtium is a genus of five plant species in the family Brassicaceae , best known for the edible watercresses Nasturtium microphyllum and Nasturtium officinale...
spp.), wild ginseng (Panax quinquefolius), wild parsnip (Pastinaca sativa), and water parsnip (Berula
Berula
Berula is a cosmopolitan monotypic genus of flowering plant in the Apiaceae, containing the single species Berula erecta, which is known by the common name cutleaf water parsnip, or also simply water parsnip as are some other plants in Apiaceae such as Sium latifolium and Sium suave. It is easily...
spp.). One of the more common misidentifications is between water hemlock and water parsnip; both have clusters of small white flowers shaped like umbrellas, and both have the same habitat near the shore line of lakes and rivers. Differences between water parsnip and water hemlock include the water parsnip having leaves only once compound while the water hemlock has leaves which are two or three times compound. Water hemlock also has a large swelling at the stem base which water parsnip lacks. Additionally, water hemlock has bract
Bract
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis, or cone scale. Bracts are often different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture...
s at the base of each small flower cluster, not at the base of the main flower head, while water parsnip has both bracts at the base of flowers and also at the main flower head.
Other plants that look similar to Cicuta spp. but are not edible are the yarrow, (Achillea millefolium, also commonly known as common yarrow, gordaldo, nosebleed plant, old man's pepper, sanguinary, milfoil, soldier's woundwort, thousand-leaf, and thousand-seal), cow Parsnip (Heracleum lanatum, also known as Heracleum maxinium, Indian celery or pushki) or hogweed (Heracleum sphondylium). Features which differentiate them include the yarrow having feathery looking leaves which are pinnately
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
separated into small narrow segments, while cow parsnip and hogweed have large, broad leaves, and an unpleasant odor.
Additionally, there can be confusion between the various water hemlock species and poison hemlock (Conium maculatum) as the common name hemlock is applied to both Cicuta and Conium maculatum. Both are poisonous and can be differentiated by differences in their root structure. Water hemlock has a branched root systems with tubules, while poison hemlock has a single tap root. Another reliable method to identify water hemlock is to examine the leaf veins. Water Hemlock is unique in the Apiaceae family in that it has leaf veins which terminate in the notches between the leaf tips, rather than extend to the tip of the leaf, as is found in the leaf structure of other members of this family.
Distribution and habitat
Cicuta spp. are found growing across North America and Europe. Typically, they grow in wet habitats usually alongside ponds and streams, in marshes or swamps, or areas that are swampy at least part of the year. Plants can also be found growing in water. Of the four species, Cicuta maculataCicuta maculata
Cicuta maculata is a species of flowering plant in the carrot family known by several common names, including spotted water hemlock, spotted parsley, spotted cowbane, and the suicide root by the Iroquois. It is native to nearly all of North America, from northern Canada to southern Mexico...
has the most widespread distribution occurring across the majority of North America. Cicuta bulbifera also has a relatively large distribution, found throughout Northern North America. Cicuta douglasii is found in the northwest corner of North America, while Cicuta virosa
Cicuta virosa
Cicuta virosa is a species of Cicuta, native to northern and central Europe, northern Asia and northwestern North America. It is a perennial herbaceous plant which grows up to 1–2 m tall. The stems are smooth, branching, swollen at the base, purple-striped, and hollow except for partitions at the...
is only found in central Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and in the far north of North America.
Toxicity
Cicutoxin
Cicutoxin is a poisonous polyyne and alcohol found in various plants, most notably water hemlock . It is structurally related to the oenanthotoxin of hemlock water dropwort....
, an unsaturated
Saturation (chemistry)
In chemistry, saturation has six different meanings, all based on reaching a maximum capacity...
aliphatic
Aliphatic compound
In organic chemistry, aliphatic compounds are acyclic or cyclic, non-aromatic carbon compounds.Thus, aliphatic compounds are opposite to aromatic compounds.- Structure :...
alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
that is structurally
Chemical structure
A chemical structure includes molecular geometry, electronic structure and crystal structure of molecules. Molecular geometry refers to the spatial arrangement of atoms in a molecule and the chemical bonds that hold the atoms together. Molecular geometry can range from the very simple, such as...
closely related to the toxin oenanthotoxin
Oenanthotoxin
Oenanthotoxin is a toxin extracted from hemlock water dropwort and other plants of the genus Oenanthe. It is a central nervous system poison, and acts as a noncompetitive gamma-aminobutyric acid antagonist. This toxin played some role in euthanasia in ancient Sardinia, for inducing risus...
found in the plant hemlock water dropwort
Water dropwort
The water dropworts, Oenanthe , are a genus of plants in the family Apiaceae. Most of the species grow in damp ground, in marshes or in water....
. Cicutoxin is present at all stages of growth and in all parts of the plant, but is most concentrated in the roots which appear to be the most toxic in the early spring. Its primary toxic effect is to act as a stimulant in the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
. It is a non-competitive gamma-aminobutyric acid
Gamma-aminobutyric acid
γ-Aminobutyric acid is the chief inhibitory neurotransmitter in the mammalian central nervous system. It plays a role in regulating neuronal excitability throughout the nervous system...
(GABA) receptor antagonist
Receptor antagonist
A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a receptor, but blocks or dampens agonist-mediated responses...
. Cicutoxin acts on the GABAA receptor causing a block of the chloride channel
Chloride channel
Chloride channels are a superfamily of poorly understood ion channels consisting of approximately 13 members.Chloride channels display a variety of important physiological and cellular roles that include regulation of pH, volume homeostasis, organic solute transport, cell migration, cell...
which results in neuronal depolarization. In the presence of cicutoxin this depolarization continues unabated causing cell overactivity. The hyperactivity in brain cells results in seizures. Cicutoxin is highly poisonous and water hemlock is considered one of North America's most toxic plants. Ingestion of Cicuta can be fatal in humans and there are reports in the medical literature of severe poisoning and death as early as 1670. A number of people have also died following ingestion of the plant in the 20th and 21st century.
The in mice administered cicutoxin by intraperitoneal injection
Intraperitoneal injection
Intraperitoneal injection or IP injection is the injection of a substance into the peritoneum . IP injection is more often applied to animals than humans...
is 48.3 mg per kg body weight
Body weight
The term body weight is used in daily English speech as well as in the contexts of biological and medical sciences to describe the mass of an organism's body. Body weight is measured in kilograms throughout the world, although in some countries it is still measured in pounds or stones and pounds...
(mg/kg); this compares with 5.9 mg/kg for mice given potassium cyanide
Potassium cyanide
Potassium cyanide is an inorganic compound with the formula KCN. This colorless crystalline compound, similar in appearance to sugar, is highly soluble in water. Most KCN is used in gold mining, organic synthesis, and electroplating. Smaller applications include jewelry for chemical gilding and...
by intraperitoneal injection
Intraperitoneal injection
Intraperitoneal injection or IP injection is the injection of a substance into the peritoneum . IP injection is more often applied to animals than humans...
, while the LD50 for arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
via intraperitoneal injection in mice is 46.2 mg/kg. The exact toxic dose of plant material in humans is unknown; it is thought ingestion of water hemlock in any quantity can result in poisoning and very small amounts may lead to death. Poisoning has been reported following children blowing whistles made from the hollow stem of water hemlock plants. Intoxication has also been reported following skin contact with the plant; a case was reported where a family of five people rubbed the plant onto the skin and were poisoned, with two children dying. Livestock
Livestock
Livestock refers to one or more domesticated animals raised in an agricultural setting to produce commodities such as food, fiber and labor. The term "livestock" as used in this article does not include poultry or farmed fish; however the inclusion of these, especially poultry, within the meaning...
have long been the worst affected, leading to the common name "cowbane". Poisoning in livestock is common and typically occurs following ingestion of roots of the plant. In the spring when the ground is soft, grazing animals tend to pull the entire plant out of the ground ingesting both the foiliage and the roots. Roots exposed by ploughing can also be the source of livestock poisonings. Ingestion of plant material may cause death in the animal in as little as 15 minutes.
Symptoms
Upon consumption, both in humans and other species, the symptoms of poisoning are mainly characterized by generalized seizures. The onset of symptoms following ingestion may be as soon as 15 minutes post ingestion. Initial symptoms reported may include nauseaNausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...
, vomiting
Vomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...
, abdominal pain
Abdominal pain
Abdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem...
, tremor
Tremor
A tremor is an involuntary, somewhat rhythmic, muscle contraction and relaxation involving to-and-fro movements of one or more body parts. It is the most common of all involuntary movements and can affect the hands, arms, eyes, face, head, vocal folds, trunk, and legs. Most tremors occur in the...
s, confusion
ConFusion
ConFusion is an annual science fiction convention organized by the Stilyagi Air Corps and its parent organization, the Ann Arbor Science Fiction Association. Commonly, it is held the third weekend of January. It is the oldest science fiction convention in Michigan, a regional, general SF con...
, weakness, dizziness
Dizziness
Dizziness refers to an impairment in spatial perception and stability. The term is somewhat imprecise. It can be used to mean vertigo, presyncope, disequilibrium, or a non-specific feeling such as giddiness or foolishness....
, and drowsiness; although the rapid onset of seizure activity may be the first sign presenting following poisoning. Seizures are usually described as clonic or tonic–clonic. Complications of ongoing seizure activity include increased body temperature
Hyperthermia
Hyperthermia is an elevated body temperature due to failed thermoregulation. Hyperthermia occurs when the body produces or absorbs more heat than it can dissipate...
, decreases in the pH of the blood
Metabolic acidosis
In medicine, metabolic acidosis is a condition that occurs when the body produces too much acid or when the kidneys are not removing enough acid from the body. If unchecked, metabolic acidosis leads to acidemia, i.e., blood pH is low due to increased production of hydrogen by the body or the...
(metabolic acidosis), swelling in the brain
Cerebral edema
Cerebral edema or cerebral œdema is an excess accumulation of water in the intracellular or extracellular spaces of the brain.-Vasogenic:Due to a breakdown of tight endothelial junctions which make up the blood-brain barrier...
, blood coagulation disorders
Coagulopathy
Coagulopathy is a condition in which the blood’s ability to clot is impaired. This condition can cause prolonged or excessive bleeding, which may occur spontaneously or following an injury or medical and dental procedures.The normal clotting process depends on the interplay of various proteins in...
, muscle breakdown
Rhabdomyolysis
Rhabdomyolysis is a condition in which damaged skeletal muscle tissue breaks down rapidly. Breakdown products of damaged muscle cells are released into the bloodstream; some of these, such as the protein myoglobin, are harmful to the kidneys and may lead to kidney failure...
(rhabdomyolysis), and kidney failure. Additional neurological symptoms may include hallucinations, delirium
Delirium
Delirium or acute confusional state is a common and severe neuropsychiatric syndrome with core features of acute onset and fluctuating course, attentional deficits and generalized severe disorganization of behavior...
, tingling, pricking, or numbness of a person's skin
Paresthesia
Paresthesia , spelled "paraesthesia" in British English, is a sensation of tingling, burning, pricking, or numbness of a person's skin with no apparent long-term physical effect. It is more generally known as the feeling of "pins and needles" or of a limb "falling asleep"...
, dilated pupils
Mydriasis
Mydriasis is a dilation of the pupil due to disease, trauma or the use of drugs. Normally, the pupil dilates in the dark and constricts in the light to respectively improve vividity at night and to protect the retina from sunlight damage during the day...
, and coma
Coma
In medicine, a coma is a state of unconsciousness, lasting more than 6 hours in which a person cannot be awakened, fails to respond normally to painful stimuli, light or sound, lacks a normal sleep-wake cycle and does not initiate voluntary actions. A person in a state of coma is described as...
. Cardiovascular symptoms include alternating slow
Bradycardia
Bradycardia , in the context of adult medicine, is the resting heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min. It may cause cardiac arrest in some patients, because those with bradycardia may not be pumping enough oxygen to their heart...
or fast heart rate
Tachycardia
Tachycardia comes from the Greek words tachys and kardia . Tachycardia typically refers to a heart rate that exceeds the normal range for a resting heart rate...
and alternating low
Hypotension
In physiology and medicine, hypotension is abnormally low blood pressure, especially in the arteries of the systemic circulation. It is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the...
and high blood pressure
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
. Other cardiac effects may include ECG abnormalities such as widening of the PR interval
PR interval
In electrocardiography, the PR interval is measured from the beginning of the P wave to the beginning of the QRS complex. It is usually 120 to 200 ms long. On the usual 25 mm/s ECG tracing, this corresponds to 3 to 5 small boxes. The PR interval reflects the time the electrical impulse takes to...
, supraventricular tachycardia
Supraventricular tachycardia
Supraventricular tachycardia is a general term that refers to any rapid heart rhythm originating above the ventricular tissue. Supraventricular tachycardias can be contrasted to the potentially more dangerous ventricular tachycardias - rapid rhythms that originate within the ventricular...
, and ventricular fibrillation
Ventricular fibrillation
Ventricular fibrillation is a condition in which there is uncoordinated contraction of the cardiac muscle of the ventricles in the heart, making them quiver rather than contract properly. Ventricular fibrillation is a medical emergency and most commonly identified arrythmia in cardiac arrest...
. Symptoms of excess salivation, wheezing, respiratory distress
Dyspnea
Dyspnea , shortness of breath , or air hunger, is the subjective symptom of breathlessness.It is a normal symptom of heavy exertion but becomes pathological if it occurs in unexpected situations...
, and absence of breathing
Apnea
Apnea, apnoea, or apnœa is a term for suspension of external breathing. During apnea there is no movement of the muscles of respiration and the volume of the lungs initially remains unchanged...
have also been reported.
Deaths usually occur from respiratory failure
Respiratory failure
The term respiratory failure, in medicine, is used to describe inadequate gas exchange by the respiratory system, with the result that arterial oxygen and/or carbon dioxide levels cannot be maintained within their normal ranges. A drop in blood oxygenation is known as hypoxemia; a rise in arterial...
or ventricular fibrillation
Ventricular fibrillation
Ventricular fibrillation is a condition in which there is uncoordinated contraction of the cardiac muscle of the ventricles in the heart, making them quiver rather than contract properly. Ventricular fibrillation is a medical emergency and most commonly identified arrythmia in cardiac arrest...
secondary to ongoing seizure activity; fatalities have occurred within a few hours of ingestion. Poisoned people who recover usually regain consciousness and seizures cease within 24 to 48 hours of poisoning, although seizures may persist for up to 96 hours. There are occasional long-term effects such as retrograde amnesia
Retrograde amnesia
Retrograde amnesia is a loss of access to events that occurred, or information that was learned, before an injury or the onset of a disease....
of the events leading to intoxication and the intoxication itself. Other ongoing mild effects may include restlessness
Anxiety
Anxiety is a psychological and physiological state characterized by somatic, emotional, cognitive, and behavioral components. The root meaning of the word anxiety is 'to vex or trouble'; in either presence or absence of psychological stress, anxiety can create feelings of fear, worry, uneasiness,...
, muscle weakness
Muscle weakness
Muscle weakness or myasthenia is a lack of muscle strength. The causes are many and can be divided into conditions that have true or perceived muscle weakness...
, twitching
Fasciculation
A fasciculation , or "muscle twitch", is a small, local, involuntary muscle contraction and relaxation visible under the skin arising from the spontaneous discharge of a bundle of skeletal muscle fibers...
, and anxiety
Anxiety
Anxiety is a psychological and physiological state characterized by somatic, emotional, cognitive, and behavioral components. The root meaning of the word anxiety is 'to vex or trouble'; in either presence or absence of psychological stress, anxiety can create feelings of fear, worry, uneasiness,...
. Complete resolution of symptoms may take a number of days or, in some cases, these ongoing symptoms may persist for months after poisoning.
Diagnosis and treatment
Water hemlock poisoning is usually diagnosed following a history of plant ingestion and symptoms of abrupt onset of seizures. Laboratory tests to determine the presence of cicutoxin in the blood such as spectrofluorimetry, high pressure liquid chromatography, thin layer chromatographyThin layer chromatography
Thin layer chromatography is a chromatography technique used to separate mixtures. Thin layer chromatography is performed on a sheet of glass, plastic, or aluminum foil, which is coated with a thin layer of adsorbent material, usually silica gel, aluminium oxide, or cellulose...
, and mass spectrometry
Mass spectrometry
Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of charged particles.It is used for determining masses of particles, for determining the elemental composition of a sample or molecule, and for elucidating the chemical structures of molecules, such as peptides and...
have been used to detect cicutoxin but these tests are not performed routinely in hospital laboratories
Medical laboratory
A medical laboratory or clinical laboratory is a laboratory where tests are done on clinical specimens in order to get information about the health of a patient as pertaining to the diagnosis, treatment, and prevention of disease.-Departments:...
. If a sample of the plant ingested has been retained, diagnosis can be confirmed by having the plant identified by a botanist.
Initial treatment of poisoning may include gastrointestinal decontamination with activated charcoal. Decontamination is typically only performed if a potentially toxic amount of plant matter has been ingested up to one hour previously and the patient has an normal intact airway
Airway
The pulmonary airway comprises those parts of the respiratory system through which air flows, conceptually beginning at the nose and mouth, and terminating in the alveoli...
or has been intubated
Intubation
Tracheal intubation, usually simply referred to as intubation, is the placement of a flexible plastic or rubber tube into the trachea to maintain an open airway or to serve as a conduit through which to administer certain drugs...
. There is no specific antidote for water hemlock poisoning and treatment mainly consists of supportive care. Treatment may include control of seizure
Seizure
An epileptic seizure, occasionally referred to as a fit, is defined as a transient symptom of "abnormal excessive or synchronous neuronal activity in the brain". The outward effect can be as dramatic as a wild thrashing movement or as mild as a brief loss of awareness...
s with the administration of a benzodiazepine
Benzodiazepine
A benzodiazepine is a psychoactive drug whose core chemical structure is the fusion of a benzene ring and a diazepine ring...
s such as lorazepam
Lorazepam
Lorazepam is a high-potency short-to-intermediate-acting 3-hydroxy benzodiazepine drug that has all five intrinsic benzodiazepine effects: anxiolytic, amnesic, sedative/hypnotic, anticonvulsant, antiemetic and muscle relaxant...
or diazepam
Diazepam
Diazepam , first marketed as Valium by Hoffmann-La Roche is a benzodiazepine drug. Diazepam is also marketed in Australia as Antenex. It is commonly used for treating anxiety, insomnia, seizures including status epilepticus, muscle spasms , restless legs syndrome, alcohol withdrawal,...
, or if seizures are refractory to this treatment, a barbiturate
Barbiturate
Barbiturates are drugs that act as central nervous system depressants, and can therefore produce a wide spectrum of effects, from mild sedation to total anesthesia. They are also effective as anxiolytics, as hypnotics, and as anticonvulsants...
such as phenobarbital
Phenobarbital
Phenobarbital or phenobarbitone is a barbiturate, first marketed as Luminal by Friedr. Bayer et comp. It is the most widely used anticonvulsant worldwide, and the oldest still commonly used. It also has sedative and hypnotic properties but, as with other barbiturates, has been superseded by the...
is administered. The anticonvulsant
Anticonvulsant
The anticonvulsants are a diverse group of pharmaceuticals used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of bipolar disorder, since many seem to act as mood stabilizers, and in the treatment of neuropathic pain. The goal of an...
phenytoin
Phenytoin
Phenytoin sodium is a commonly used antiepileptic. Phenytoin acts to suppress the abnormal brain activity seen in seizure by reducing electrical conductance among brain cells by stabilizing the inactive state of voltage-gated sodium channels...
is not recommended as it has not been shown to be effective for seizure control following water hemlock poisoning. Treatment with high doses of benzodiazepines or barbiturates may cause respiratory depression and respiratory support including intubation
Intubation
Tracheal intubation, usually simply referred to as intubation, is the placement of a flexible plastic or rubber tube into the trachea to maintain an open airway or to serve as a conduit through which to administer certain drugs...
and mechanical ventilation
Mechanical ventilation
In medicine, mechanical ventilation is a method to mechanically assist or replace spontaneous breathing. This may involve a machine called a ventilator or the breathing may be assisted by a physician, respiratory therapist or other suitable person compressing a bag or set of bellows...
is required in these patients. Continuous electroencephalography
Electroencephalography
Electroencephalography is the recording of electrical activity along the scalp. EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain...
monitoring is recommended in symptomatic patients.
Further treatment for complications of metabolic acidosis
Metabolic acidosis
In medicine, metabolic acidosis is a condition that occurs when the body produces too much acid or when the kidneys are not removing enough acid from the body. If unchecked, metabolic acidosis leads to acidemia, i.e., blood pH is low due to increased production of hydrogen by the body or the...
, rhabdomyolysis
Rhabdomyolysis
Rhabdomyolysis is a condition in which damaged skeletal muscle tissue breaks down rapidly. Breakdown products of damaged muscle cells are released into the bloodstream; some of these, such as the protein myoglobin, are harmful to the kidneys and may lead to kidney failure...
, hyperthermia
Hyperthermia
Hyperthermia is an elevated body temperature due to failed thermoregulation. Hyperthermia occurs when the body produces or absorbs more heat than it can dissipate...
, or low blood pressure may be required. Metabolic acidosis is treated by administering sodium bicarbonate
Sodium bicarbonate
Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula Na HCO3. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda . The natural mineral form is...
. Low blood pressure is usually treated with intravenous fluid replacement
Fluid replacement
Fluid replacement or fluid resuscitation is the medical practice of replenishing bodily fluid lost through sweating, bleeding, fluid shifts or other pathologic processes. Fluids can be replaced via oral administration , intravenous administration, rectally, or hypodermoclysis, the direct injection...
, but the administration of dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
or norepinephrine
Norepinephrine
Norepinephrine is the US name for noradrenaline , a catecholamine with multiple roles including as a hormone and a neurotransmitter...
may be required to restore blood pressure. The management of rhabdomyolysis includes ensuring adequate hydration and urinary alkalinization; a complication of rhabdomyolysis is acute renal failure which may require management with hemodialysis
Hemodialysis
In medicine, hemodialysis is a method for removing waste products such as creatinine and urea, as well as free water from the blood when the kidneys are in renal failure. Hemodialysis is one of three renal replacement therapies .Hemodialysis can be an outpatient or inpatient therapy...
. However, hemodialysis, hemoperfusion
Hemoperfusion
Hemoperfusion is a medical process used to remove toxic substances from a patient's blood. The technique involves passing large volumes of blood over an adsorbent substance. The adsorbent substance most commonly used in hemoperfusion are resins and activated carbon...
or other extracorporeal
Extracorporeal
An extracorporeal medical procedure is a medical procedure which is performed outside the body.-Circulatory procedures:A procedure in which blood is taken from a patient's circulation to have a process applied to it before it is returned to the circulation...
techniques do remove cicutoxin from the blood and are therefore not useful in enhancing elimination.