Cicuta, commonly known as water hemlock, is a genus of four species of highly poisonous plants in the family Apiaceae. They are perennial herbaceous plants which grow up to 2.5 meters (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 edible or poisonous plants. The common name hemlock may also be confused with poison hemlock (Conium maculatum), or with the Hemlock tree.
Water hemlock is considered one of North America's most toxic plants, being highly poisonous to humans.[1] Three members of the genus contain a toxin named cicutoxin which causes central nervous system stimulatory effects including seizures 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 meters (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 rootstocks. 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 pinnately compound and may reach 30 centimeters (12 in) to 90 centimeters (35 in) in length. The leaflets are lanceolate, serrate, 5 centimeters (2.0 in) to 10 centimeters (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 centimeters (2.0 in) to 10 centimeters (3.9 in) across. The plants produce a cylindrical fruit which is 4 millimeters (0.16 in) to 6 millimeters (0.24 in) in length.[1][2][3] The plant is spread primarily by seeds which are produced in large numbers and are small in size.[2]
The genus Cicuta is one of many genera in the family Apiaceae, which is in the order Apiales. Apiaceae is also known as Umbelliferae, and both of these family names are permitted to be used by the International Code of Nomenclature for algae, fungi, and plants.[1] 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.[2] Carl Linnaeus formally described three species in 1753.[4] The type species is Cicuta virosa.[5] The genus is now recognized to comprise four species:[6]