The plants have branching stems, swollen at the base, purple-striped, or mottled, and hollow except for partitions at the junction of the leaves. The leaves are alternate, tripinnate only coarsely toothed. The flowers are small, white and clustered in compound umbels.
The genus Cicuta is the most virulently poisonous group of flowering plants native to the north temperate zone.
Four species belonging to the Cicuta genus are found in North america, but only three are found in Québec:
Cicuta quoque venenum est, publica Atheniensium poena invisa, ad multa tamen usus non omittendi. semen habet noxium; caulis autem et viridis estur a plerisque et in patinis. levis hic et geniculatus ut calami, nigricans, altior saepe binis cubitis, in cacuminibus ramosus, folia coriandri teneriora, gravia odoratu, semen aneso crassius, radix concava, nullius usus. Semini et foliis refrigeratoria vis; sic et necat: incipiunt algere ab extremitatibus corporis.
that translates to :
Hemlock (Cicuta maculata), too, is a poisonous plant, rendered odious by the use made of it by the Athenian people, as an instrument of capital punishment: still, however, as it is employed for many useful purposes, it must not be omitted. It is the seed that is noxious, the stalk being eaten by many people, either green, or cooked in the saucepan. This stem is smooth, jointed like a reed, of a swarthy hue, often as much as two cubits in height, and branchy at the top. The leaves are like those of coriander, only softer, and possessed of a powerful odor. The seed is more substantial than that of anise, and the root is hollow and never used. The seed and leaves are possessed of refrigerating properties; indeed, it is owing to these properties that it is so fatal, the cold chills with which it is attended commencing at the extremities.
although I'm not sure that that the stalk might be eaten either green, or cooked in the saucepan, without impunity!
The word (Cicuta) is also referred to by Marcus Porcius Cato, Cato the Elder, (234 BC, Tusculum 149 BC) who was bred, after the manner of his Latin forefathers, to agriculture, to which he devoted himself when not engaged in military service. His book on running a farm, De Agri Cultura (On Farming), his only work that survives completely, is a miscellaneous collection of rules of husbandry and management including sidelights on the Roman country life in the 2nd century BC.
But the scientific name of Hemlock is Conium and is derived the Greek word χωνειον (khôneion) and is referred to, in Latin, as Conium, by Saint Ambrose (born between 337 and 340 AD., died on the 4th of April 397). He was a bishop of Milan who became one of the most influential ecclesiastical figures of the fourth century. He refers to the word in his Hexaemeron (commentaries on the Old Testament).
So there was some mix-up in choosing the proper genus name for Cicuta maculata and for Conium maculatum in reference to classical sources ! But since both are quite poisonous...
The chief poison is cicutoxin, an unsaturated aliphatic alcohol that is most concentrated in the roots. Upon human consumption, nausea, vomiting, and tremors occur within 30 to 60 minutes, followed by severe cramps, projectile vomiting, and convulsions. There are occasional long-term effects, like retrograde amnesia. Ingestion in any quantity can result in death or permanent neurological damage of the central nervous system. Cicuta poisoning has a case-fatality rate of 30%.
One reliable method to identify a species belonging to the Cicuta genus is to examine the leaf veins. These species are unique in the Apiaceae family in that the leaf veins terminate in the notches between the leaf tips instead of extending to the tip of the leaf.