Water hemlock or spotted cowbane
Cicuta maculata
Parsley (Apiaceae) Family

Water Hemlock or Spotted Cowbane plant

Description: The Water Hemlock, also known as spotted water hemlock, spotted parsley, spotted cowbane, and the suicide root, is perennial herb in the carrot family.  It is very difficult to distinguish it from other, similar looking plants.  Water Hemlock may grow to 1.8 meters (6 feet) high. The stem is smooth, hollow (solid when very young) and sectioned off like bamboo and is often purple or red striped or mottled on mature plants.

Its 2-5 inch leaves are made up of several leaflets that are small, shiny, green, lance-shaped, and pointed with sharply toothed edges.  The lower leaves are large and long stalked while the upper leaves are divided into three leaflets and each again divided into three (twice ternate).

Water Hemlock plant growing near waterIts flowers are small (no more than 1/8 inch across), have five petals, green or white, and grow in clusters that tend to form flat umbels giving them the appearance of white, rough skinned umbrellas. Its whorls of slender, fibrous roots may have hollow air chambers and, when cut, may produce drops of yellow oil which turns reddish-brown when exposed to air.  Its cylindrical or oval-shaped fruit is dry, tan or brown, only a few millimeters long and ribbed on the outer surface.

Flowers of the Water Hemlock plantIts appearance to water parsnips is similar.  The primary difference is in the leaf structure.  Water parsnips have leaves that are only once compound while Water Hemlock has leaves that are three times compound.  Water hemlock also has a large swelling at the stem base which water parsnip lacks.  In addition, careful examination of a water parsnip leaf will show the vein running to the pointed end of the toothed edge whereas with Water Hemlock, the vein runs to the edge of the leaflet in between the toothed edges.  Also, the water hemlock has bracts at the end of each flower cluster whereas water parsnip has bracts at both the base of the flowers and main flower head.

The Water Hemlock may be distinguished from the true Hemlock as follows: (i) The pinnae of the leaves are larger and lance shaped; (ii) the umbel of the flowers is denser and more compact; (iii) the stem is not spotted like the true Hemlock; (iv) the odor of the plant resembles that of parsley.

Water Hemlock plant and white clustere flower headThis plant is very poisonous and even a very small amount of this plant may cause death.  Children have been poisoned simply by using the plant’s hollow stem as a whistle and persons have been poisoned simply by rubbing the plant’s outer surface.   Its roots have been mistaken for parsnips. It is considered to be North America’s most toxic plant.  The majority of the poison is concentrated in its roots.

Symptoms of poisoning include nausea, vomiting, severe cramps, tremors, confusion, weakness, dizziness, drowsiness, hallucinations, delirium, tingling, numbness in the skin, dilated pupils, and violent and painful convulsions.  Results of these symptoms can causes brain swelling, muscle breakdown, and kidney failure.  It can cause death in as little as 15 minutes.  It also can cause long-term, permanent neurological damage.  In addition to anti-convulsant drugs, activated charcoal may be administered to slow toxic poisoning (if it is administered soon after ingestion).  There is no antidote and medical treatment consists of supportive care only.

Habitat and Distribution: Water hemlock grows in wet or moist ground like swamps, wet meadows, stream banks, lakes, rivers, and ditches throughout the Unites States and Canada.  They can also be found growing in water.

Water Hemlock plant growing in the wild

Close-up of Water Hemlock leaves and flowers

Sample of Water Hemlock stem and leaves

Drawing of the Water Hemlock plant

Color drawing of the Water Hemlock plant illustrating the plant's stems, leaves, seeds, fruit, and root structure

Drawing of the Water Hemlock plant illustrating the plant's components