Cicuta douglasii (Western water hemlock) is a poisonous plant in the family Apiaceae. It is a perennial plant that grows in wet places such as marshes, stream banks, slough margins, ditches, meadows, and wet pastures. The roots of this plant are thick and tuberous, with many smaller tubers coming from the main tuber. This root structure allows the water hemlock to adapt and survive wet conditions. Water hemlock is most abundant in British Columbia, and is indigenous to North America. In North America it primarily grows from the base of the Rocky Mountains to the Pacific coast, stretching all the way from Alaska down to California. Water necessities limit this plant from growing in open rangelands.