Field Guide to Plants Poisonous to Livestock: Western U.S.
Common names: Water hemlocks
Habitat: Wetlands, streamsides
Toxic season: Year-round
Features: Branched, leafy plant up to 10' tall, stems primarily hollow. Root stalk comprised of hollow, horizontal chambers containing yellow liquid. Leaves alternate, compound with lance-shaped, toothed leaflets. Certain identification can be made due to leaf veins ending in notches. Flowers small, white in umbrella-like clusters. Seeds tan, kidney-shaped with cork-like ridges.
Poison type: Highly unsaturated higher alcohol (cicutoxin)
Signs/effects: Violent central nervous system effects: initial signs are excessive salivation/frothing at the mouth, incoordination, nervousness, and occur rapidly after ingestion of lethal amount, followed by muscle twitching, rapid pulse/breathing, dilation of pupils, tremors, intense convulsions, pain, coma. Death may be very rapid and violent.
Treatment: Barbiturates, if administered before seizures begin, may prevent death. Activated charcoal, if ingestion recent, fluids, seizure control are other possible interventions. Animals alive 2 hours after ingestion may recover.
Comments: Extremely poisonous. All parts highly toxic, esp. liquid in root chambers. May be eaten in spring when other forage unavailable. Animals have been poisoned by drinking water contaminated with trampled plant material. Use caution when removing plants - highly toxic to humans.
© Copyright 1998 by Shirley A. Weathers