Water hemlock belongs to the family Apiaceae (Umbelliferae). The genus Cicuta includes the species spotted water hemlock (C. maculata), Western water hemlock (C. douglasii), and northern water hemlock also known as European water hemlock (C. virosa), C. bolanderi, C. bulbifera, C. californica, C. curtissii, C. mackenziana, C. occidentalis, and C. vagans (Figs. 1, 2, and 3). The active toxic compound in water hemlock is cicutoxin. The hemlock water dropwort (Oenanthe crocata) belongs to the family Apiaceae (Umbelliferae), genus Oenanthe. It is native to Europe but has been introduced to some parts of the United States. It lacks the chambered root of the Cicuta spp. and produces oenanthotoxin, a constitutional isomer (a compound that has the same molecular formula but a different structural formula) of cicutoxin. The various species of Cicuta and Oenanthe have approximately equivalent clinical toxicity at similar stages of plant growth, producing virtually identical clinical manifestations in poisoning, and, therefore, will be discussed as a single group. Common names of these plants include cowbane, children's bane, poison parsnip, five-fingered root, dead men's fingers, death-of-man, wild parsnip, snakeroot, snakeweed, beaver poison, muskrat weed, spotted hemlock, spotted cowbane, musquash root, false parsley, poison hemlock, wild carrot, fever root, mock-eel root, spotted parsley, cique vireuse, and carotte à moreau. Water hemlock species are biennial or perennial plants that grow to a height of 6-8 ft with