(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 family Apiaceae 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 maculata 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 found in central and northern Europe (including the British Isles), northern Eurasia, and in the far north of North America. Toxicity All members of Cicuta 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. This hyperactivity in brain cells results in seizures. Cicutoxin is very 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 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