How to Identify Water Hemlock

by Ben Team
A marsh lined by trees.

A marsh lined by trees.

Water hemlock is an easily misidentified plant that is often confused with edible weeds and shrubs. As a potentially lethal species, you must avoid eating any similar-looking plants that you cannot identify with certainty. While several traits allow you to identify the species, the leaves provide the best clues.

Very Important Veins

  1. The leaf veins of water hemlocks provide the most helpful diagnostic tool. While most plants have veins that terminate at the tips of the teeth along the leaf margin, the veins of water hemlocks end in the notches located between the teeth. Water hemlock is the only species in the carrot family to display such a trait.

Similar Species

  1. Water hemlock is a common perennial plant, often found in wet meadows and along bodies of water. Like several other similar-looking species, such as water parsnip and wild carrot, water hemlock is an herbaceous plant, with white, umbrella-shaped flowers. However, wild carrot has thorny or hairy stems, while water hemlock stems bear neither. Distinguish water hemlock from water parsnip by noting the doubly compound leaves of the former and the singly compound leaves of the latter. Another similar-looking plant – cow parsnip – has umbrella-like flowers, but its leaves are divided into three distinct lobes, which differ from the lance-shaped leaflets of water hemlock.

Proceed With Caution

  1. Called the most “violently toxic plant” in North America by the United States Department of Agriculture, water hemlock can kill humans in a matter of minutes. Ingestion of even a tiny portion of the plant requires immediate medical attention. While the bulk of the toxins are located in the root, all portions of the plant are toxic.

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