A biennial native of Europe, this plant usually grows to a height of 4 to 8 feet tall. It has a hollow smooth stem with distinctive reddish to purple spots. Leaves are lacy and fern-like, similar in appearance to parsley. Flowers are white and borne in umbrella-shaped clusters at the end of individual stalks. All parts of the plant contain alkaloids and are poisonous to livestock and humans.
Hemlocks can tolerate poorly drained soils and are found near roadside ditches, rivers, and streams. The plant can be mistaken for wild carrot or parsley which is the cause for most cases of human poisoning. Poison hemlock has been found along both Garfield and Baldy creeks.