Marshes and shores, swamps, moist to wet forests and thickets, stream banks, meadows, ditches.

Usually considered to be the most violently poisonous plant in temperate North America, for both livestock and humans. Poison is concentrated in the clustered tuberous roots, although all parts of the plant are poisonous. Symptoms appear promptly and include abdominal pain, violent convulsions, fever, paralysis, and respiratory failure, followed by death, sometimes within 15 minutes, or as long as 8 hours later.