Water hemlocks (Cicuta spp.)

Water hemlocks (Cicuta spp.)

~ Warning: Toxic – this profile is for botanical interest only, not for medicinal use, and I do not recommend any physical contact with plants in this genus, nor will I be held responsible for any incidents that result from those who ignore the warning. ~

water hemlock

Diagram courtesy of Prof. Dr. Otto Wilhelm Thomé Flora von Deutschland, Österreich und der Schweiz 1885, Gera, Germany.

The following information may not be re-posted, copied or published without my permission and appropriate credit given. Please contact me via email (listed on the About page) if you wish to re-publish any of the information on my blog.

There are many poisonous plants out there, and some of us are rather infatuated with these edgy members of botanical society. Because the plant spirits are tricky little devils, they often create poisonous varieties that look, smell, taste or feel just like their non-toxic relatives. I proudly present to you, the water hemlocks.

Other common names: Spotted Cowbane, spotted water hemlock

Family: Apiaceae

A day in the life:

Water hemlocks (there are four species in the Cicuta genus) have the distinction of being some of North America’s most toxic plants, with the ability to nix a human in minutes. Some get it confused with parsnip, and it grows on riverbanks, swamp or wetland areas most often. The most toxic part is the root, however the aerial parts are also toxic, even (to a lesser extent) when dried. Water hemlocks grow most prolifically in the Northern hemisphere, particularly Europe and North America.

Don’t mistake it for: Angelica, cow parsnip, members of the parsley family such as wild carrot (Queen Anne’s Lace).


Chemical structure of cicutoxin. Diagram courtesy of Wikimedia Commons/User: Minutemen.

Tricks for identifying:

  • Look for (but don’t touch) a stem with a purple tinge. Not all water hemlock species have this characteristic, but it is one potential indicator that you are dealing with one.
  • Stems tend to be hollow, smooth and hardy, and can be either solid-coloured or mottled.
  • Water hemlock flowers in spring and early summer. The blooms are small, white or green, and they have five petals and five stamens each. Their petals are notched at the tips. They are arranged in an umbrella shaped structure like others in the apiaceae family.
  • Water hemlock leaves are alternate compound and have pointed leaflets, with sharp-toothed edges. They also have veins that end at the notches between the teeth, and may have a reddish hue (but not always).

Emergency ID method only, do not do this unless absolutely necessary, and unless you are willing to be responsible for thorough clean-up and contamination prevention:

If you’re still in doubt and NEED to know immediately (what, did one of you already eat one?), don a pair of gloves and very carefully dig up a root. Do so with great respect and do NOT damage any plant tissues as it can release toxins into the surrounding water and soil, and harm wildlife. Without making skin-to-plant contact, lay the root on a non-porous, disposable surface (like a plastic plate you won’t be using again…not a picnic table or your boyfriend’s sandwich…unless he’s a really, really bad boyfriend) and split the root with a sharp knife (which must be either disposed of or cleaned very carefully afterwards and not rinsed in a natural water source where it may contaminate – if you use a sink, you must clean the sink after).


Photo courtesy of Olivier Pichard / Wikimedia Commons

If there are horizontal chambers where the stem joints the root, you can be assured you are holding true water hemlock. The root should also contain an oily, yellow substance that turns brownish red upon exposure to air, and smells of raw parsnip. Do not allow it to have prolonged contact with your skin.

Proceed with poisoning first aid if needed (see below), and wash anything that has touched this plant, being sure not to leave anything  unclean if it has been in contact with the toxin. And don’t even think about disposing of the materials anywhere that can be accessed by animals (including humans).

Toxicology info:

All the species in the genus, except for C. Bulbifera, contain circutoxin. This toxic constituent stimulates the central nervous system in excess, causing seizures and eventual death via cardiac arrest and/or paralysis of the diaphragm causing respiratory failure.

Its LD50 is just a couple of milligrams higher than that of arsenic.

Children can be killed from merely handling the plant, and some have died from either rubbing the fluid on their skin or by blowing through the hollow stems to create accidental whistles of death (AWDs).

Death occurs in as little as 15 minutes (in which case I’m sorry for rambling), or as long as a few hours.

Livestock are often poisoned when fields containing water hemlock are mowed, exposing the roots and their inner fluid.


Seizures (usually the first symptom presented), nausea/vomiting, weakness, tremors, confusion, dilated pupils, numbness or skin prickling, hallucinations, delirium, swelling in the brain, injuries from prolonged seizing, fever, blood coagulation issues, kidney failure, abdominal pain, cardiac irregularity (alternating fast and slow heartbeat), respiratory distress/wheezing, excess salivation, low blood pressure and coma.

water hemlock

Photo courtesy of Wikimedia Commons / User:BerndH

Following survival: If a patient survives a non-lethal dose of water hemlock, they usually regain consciousness and seizures stop within 24 – 48 hours. They may suffer from retrograde amnesia (specifically not recalling the events that led to the intoxication…this is the plant’s way of assisting poisoners, I think), and muscle weakness, anxiety, tremors, twitching and restlessness for days or even months after the poisoning occurred.


  1. Call 911/Poison Control
  2. Administer activated charcoal at standard dosage of 1 tablespoon per 10lbs. (1gm per kg) body weight every half hour until medical care can be sought.
  3. Administer anticonvulsant drugs, such as benzodiazepines, or herbs with similar actions such as Mongolian milk vetch or skullcap in high dosages. Exception: The anticonvulsant drug phenytoin can not be used, as it is oddly ineffective in the case of water hemlock poisoning.
  4. Apply a breathing apparatus in order to facilitate mechanical ventilation (obviously not for the layperson)
  5. If the victim survives, aftercare includes rehydration to replenish lost fluids, medications to relax the muscles and hemodialysis to restore kidney function. Dopamine and norepinephrine can be given to re-establish blood pressure normality. Conventional means of eliminating toxins from the bloodstream via chelation or dialysis are, again, strangely ineffective when dealing with water hemlock and will not remove this substance from a human body.

Disclaimer: The information on this website is intended as general education on herbs only.  

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