Water Hemlock – The Deadliest of Native Plants

But let’s look at this plant more closely, so you can better identify it and keep the kids & livestock away, as well as learn how horrible the symptoms of poisoning are as well as some fascinating Native American folklore about it.

Reference Table

Scientific Name	Cicuta maculata
Common Name(s)	Water Hemlock, beaver poison, children’s bane, cowbane, death of man, musquash root, snakeweed, spotted hemlock, spotted parsley, mock-eel root, muskrat weed, poison parsnip
Native Range, USDA Zone	North America, USDA Hardiness zones 3-9
Bloom Time	Spring
Bloom Duration, Color	Four weeks, white
Height	2-8′
Light Requirements	Full sun to part-shade
Soil Types	Sandy loam to clay loam
Moisture	Wet to moist. Can tolerate intermittent flooding.
Fauna Associations / Larval Hosts	Numerous species of pollinator feed on nectar. Hosts 8 species of moth and butterfly

Identification and Characteristics

Before I get into the key characteristics for identifying Water Hemlock, I want to preface this section by talking about plant identification apps. Please note that there are numerous apps available, and they have varying degrees of accuracy. Based on my testing, I found a few that I really liked. However, you must be very careful. Do not rely solely on plant identification apps, as they can have deadly consequences. As an example of the danger our relying solely on an identification app, I’ll show you an unlisted video I uploaded to YouTube. It is a popular plant identification app consistently mis-identifying Water Hemlock as an edible carrot. Now, I shot this is 2024, and they may have made improvements since then…..but this clearly illustrates the risks of these apps, if someone only relies on it for identification.

Stalk

Leaf

The leaves are alternately arranged, compound (sometimes doubly compound) pinnate and up to 18″ long. The leaflets are 2-4″ long by one-third as wide, linear-lanceolate to ovate-lanceolate with dentate or serrated margins^[2].

For leaf identification, a very important characteristic is that there are lateral veins on the leaflets, and these extend to the notch between teeth of the margins, not the tips.

Flower

Compound umbels of flowers are loosely arranged at the termination of the stalks.

Petals are white and there is a whorl of bracts behind the flower. Individual flowers are approximately 1/8″ diameter. The nectar resides on the surface, making it available for many pollinator species.

Root

Native Range

How Water Hemlock will kill you

Fatalities are most often from eating any part of the root, which is exceptionally poisonous. Although I did read sources that stated that children had been poisoned by blowing through the hollow stems^[2]. The plant is said to not have a terrible taste (as related by one Iroquois^[10]), which removes a common, natural prevention mechanism that many poisonous plants have (bitterness). But if you do happen to eat the root, what actually happens?

Well, the toxin that is in the plant, Cicutoxin (C₁₇H₂₂O₂)^[3], is concentrated within the roots but will be present in all parts of the plant^[2][3]. This is a neuro toxin that wastes no time effecting your nerves, and it wastes no time in harming you with symptoms occuring in as little as 15 minutes for both people and animals^[2][9]. The most common symptom is convulsions and spasms, often violent. Case studies report brief periods of rest in between the spasms. Other symptoms include vomiting and bloating. And it is said if vomiting occurs the prognosis for recovery is good^[8].

In fatal cases, as this poison spreads within the body the eventual end is by respiratory paralysis and asphyxia, so basically your heart and lungs can’t deliver enough oxygen. I find it simultaneously horrifying and fascinating how this chemical basically suffocate you while surrounded by air.

Water Hemlock and skin

While I (and you) are most concerned about the fatal effects, it has been reported that sensitive individuals may have an allergic reaction to contact with Water Hemlock. As you have seen in the leaf pictures, I have touched the leaves without issue. It would appear that this effect is fairly uncommon^[7].

Fatalities

Native Americans and Water Hemlock

As part of my research on this topic, I stumbled upon a fascinating, yet sad piece of Native American folklore. While there are several tribes that used the leaves as a poultice for arthritis, dislocated joints, and swellings^[11](that doesn’t mean you should – don’t do it), and some tribes used it to make poison arrows, there is an even darker use. The Nations of the Iroquois in particular would use this plant to commit suicide. Numerous cases are related of jaded lovers and others choosing to end their life by eating the root^[10].

Now for the folklore, William Fenton notes in his paper on Iroquois suicide: “There is an old belief that anyone contemplating suicide by taking muskrat root [sic Cicuta maculata] need not necessarily know the plant, for he can easily find it. The plant is said to call and show itself. You can go right up to it in the dark. The old people say that …when you want it, it stands up there where it grows calling you.[indian suicide]” This description related to him almost would seem that the Iroquois felt it had something akin to a demonic ability to make itself available to suicidal or depressed people. Like it wanted you to take it, almost like temptation to sin.

Livestock

Water Hemlock is just as toxic to livestock as it is humans. Since the root doesn’t necessarily taste bad, in wet pastures livestock have been known to die^[12][13]. This is a particular difficult problem, as by the time a farmer notices a problem, a large number of livestock could be too far gone to save. There are stories of farmers noticing their flock was light, and come to discover a dozen or more sheep or cattle dead near a patch of Water Hemlock. And in the past some unfortunate testing has been done to determine just how lethal it can be.

Researchers fed sheep various doses of the root to determine how much was needed to kill them, as well as trying to develop remedies for when poisoning does occur. They determined that sheep fed with 2.8 g of root per kg of their body weight recovered while those with 6.4 g/kg died within 90 minutes^[12]. Even though this is a cruel test, their intention was also to see if they could counteract the effects. And they discovered that by giving effected sheep a sedative, Sodium pentobarbital, they could often recover^[3].

Pollinators

Despite the negative effects this plant has on humans and animals, it is very useful to pollinators. Charles Robertson noted over 230 species of pollinator that visited Water Hemlock for nectar. A few long tongued bees, but many more short-tongue bees and insects such as wasps, sawflies, etc^[5]. It also hosts the Black Swallowtail caterpillar, and a few moths^[6]. Below is a listing of the species hosted:

• Agonopterix clemensella
• Depressaria cinereocostella
• Depressaria juliella
• Epermenia cicutaella
• Papaipema birdi (umbellifer borer)
• Papilio polyxenes (Black Swallowtail)
• Papilio polyxenes asterius (Eastern Black Swallowtail)
• Papilio zelicaon (Anise Swallowtail)

Lifecycle

An interesting botanical characteristic of the plant is that it isn’t a perennial, but it is……wait what? Ok, so from the tuber a stalk will emerge in Spring. And this root system will thicken as it stores energy from photosynthesis from the leaves. But once lowering begins, the root system will deplete it’s stored energy to flower and produce seed. But before it completely exhausts itself, it will produce a lateral shoot that will serve as next years start, I suppose technically this is a rhizome. As Kingsbury observed, the plant is not technically a perennial, although the plant will occupy nearly the same location year-to-year^[2].

Water Hemlock spreads via seed. A single plant can produce hundreds to thousands of seed, and they can float on water. So, this is how the plant primarily spreads. Birds may also contribute to this to a limited extent.

Controlling Water Hemlock

If you own land that is wet, or borders a pond or stream it is very possible you will encounter Water Hemlock. As long as you know what it is, and don’t eat it, it shouldn’t cause a problem. Besides, it is a native plant, and most likely found it’s way there naturally. But if you have children, or just don’t want one of the most toxic plants nearby, well, that is completely understandable. The good news is Water Hemlock is easily pulled when growing, as the soil is often so moist that the tubers come right up. You should then burn the plant, but make sure nobody (nor yourself) is downwind. I have no direct evidence that the fumes from burning Water Hemlock are harmful, but I would not take any risk.

Herbicides can also be used to control Water Hemlock. But it is noted that these herbicides may change the ‘flavor’ and make the plant more palatable to livestock before the ultimate death of the plant. So, be aware of that fact to keep your livestock away until the plant is fully dead.

Conclusion

Water Hemlock is one of the dangerous plants native to North America. The poison it contains, Cicutoxin, is one of the most lethal naturally occurring substances in the world. Most of the fatalities seem to have occurred due to mistaken identify of the root, which only reinforces that we need to be careful in identification when foraging. While that seems like common sense, it apparently is not in fact common. Or at least it has happened enough times to sadden at the loss of so many children.

Still though, this plant does provide a use for pollinators in the form of nectar. So many species feed on it! And it does host a handful of caterpillars, giving it an ecological use within our continent.

Find more native plants here!