Cicuta maculata L.—Water hemlock; cowbane; beaver poison
FAMILY: Umbelliferae (Apiaceae)—The Umbel Family
This group consists of herbs with flowers: usually regular and perfect, in a simple or compound (most common) umbel; stamens: 5, inserted on a disk: styles: 2; ovary: 1, inferior; leaves: alternate or basal, the petiole sometimes bearing a basal sheath.
PHENOLOGY: Water hemlock flowers June through August.
DISTRIBUTION: Found in marshes, swamps, ditches, streams, and marshy meadows and pastures.
PLANT CHARACTERISTICS: Flowers are in compound umbels; sepals: triangular; petals: white; stem: glabrous, jointed with hollow internodes, base of stem swollen and transversely partitioned; root: tuberous; leaves: pinnately compound with well-defined leaflets; leaflets: linear to lance-ovate, 3-10 cm long; primary lateral veins in the leaflets are directed to the crotch of the teeth; umbels: numerous, 5-12 cm wide.
POISONOUS PARTS: All parts are extremely poisonous. A piece of root the size of a pea is sufficient to kill a human. A piece of root the size of a walnut will kill a cow in fifteen minutes, and about 1 lb of dried plant may kill a horse.
SYMPTOMS: Usually within 1/2 hour after ingesting a lethal dose the following symptoms occur: excessive salivation, then tremors and spasmodic convulsions with intermittent relaxation (the convulsions are extremely violent). Abdominal pain is evident, pupils are dilated, and temperature may be several degrees higher than normal. Humans may become delirious. Nausea and vomiting occur if the animal can vomit. Bloating is common. Additional symptoms include diarrhea, irregular pulse and heart rate, and behavioral abnormalities such as rolling of the eyes, turning in circles, twisting of the neck, falling down, and opening and shutting of the mouth. Death is due to respiratory failure after complete paralysis. Postmortem: gross and histological lesions: no obvious changes.
POISONOUS PRINCIPLE: Cicutoxin, a highly unsaturated alcohol, is responsible for poisoning. It is usually associated with the yellowish, oily liquid located in the lower stem and roots.
CONFUSED TAXA: Young plants of elderberry, Sambucus spp. (Caprifoliaceae), resemble water hemlock. The leaves are opposite in elderberry and alternate in water hemlock. Elderberry may be mildly toxic. A cyanogenic glycoside, as well as an alkaloid, are present in elderberry leaves, flowers, berries, and particularly the roots. In moderate amounts these substances are purgative. Fresh berries are paradoxical--harmless when cooked but sometimes producing nausea when uncooked. Postmortem evaluation of elderberry toxicosis reveals bright red blood characteristic of cyanide poisoning.
SPECIES OF ANIMALS AFFECTED: All species of animals and humans are affected by cicutoxin.
TREATMENT: (11a)(b); (26); Convulsions can be controlled by parenteral, short-acting barbiturates.
OF INTEREST: Cattle have been poisoned by drinking water from an area where water hemlock roots were trampled.