Hemlock Water Dropwort: The Most Poisonous Plant in Britain…

…And indeed one of the most poisonous in the world. Some websites (such as Zidbits.com) even list it as the deadliest, and it never fails to reach the top ten. If you only ever learn one poisonous plant, please, let it be this one.

Hemlock Water Dropwort: Deadly

Hemlock Water Dropwort is the Death Cap of the kingdom Plantae (plant kingdom), and in fact leaves that most deadly of fungus looking rather innocuous in comparison (it’s absolutely not, mind you). Whilst the consumption of the Death Cap will leave you with about 10 days to bid your final farewells to the world (though it may be more advisable to seek medical attention), a substantial serving of Hemlock Water Dropwort will see you in the ground within 3 hours.  

The poison contained in Hemlock Water Dropwort is oenanthotoxin, and the effects after ingestion are nothing short of horrific, as summed up very succinctly by the Online Encyclopaedia of the Umbelliferae (Carrot/Parsley) Family of the British Isles: ‘Great agony, sickness, convulsions, paralysing speech, death.’


Hemlock Water Dropwort roots

The Parsnip-like roots and leaves of the deadly Hemlock Water Dropwort.

Unfortunately, there are a number of edible and very tasty species – including one of my favourites, Alexanders – with which Hemlock Water Dropwort may be quite easily confused. As you can see from the picture (right), the roots (which contain the highest concentration of oenanthotoxin) look rather parsnip-like, and as you can imagine, have been tragically mistaken for the Wild Parsnip and Water Parsnip in the past. I refer you to the online Emergency Medical Journalto read of the narrow escape had by a group of foragers after feasting on what they thought was a Wild Parsnip curry back in 2002.  The leaves, too, have found themselves mistaken for Wild Parsley and Alexanders (view the slideshow, below), and have sometimes, disastrously, even been nibbled absent-mindedly by children.

See my Poisonous Greens A-Z page for full pictures and description.

This slideshow requires JavaScript.

P.S. The dangers of foraging sometimes stretch beyond the positive identification of species. Sometimes, it is the positive identification of direction that can prove to be one’s peril.  Even though I was sufficiently familiar with Hemlock Water Dropwort to leave it well alone, after taking these pictures I found that I was certainly not at all familiar with the woodland that I was rummaging around in. I was lost! Proper lost! I had ventured off the footpath and had no idea which way I had come. Forty-five minutes later, when I finally and very shamefacedly found my way back to the car, my waiting (and heavily pregnant) wife was just about ready to throttle me… perhaps Dropwort poisoning isn’t such a bad way to go.


About J P Waldron

John Waldron is a technology and business writer for markITwrite digital content agency, based in Cornwall, UK. He writes regularly across all aspects of marketing and tech, including SEO, social media, FinTech, IoT, apps and software development.
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6 Responses to Hemlock Water Dropwort: The Most Poisonous Plant in Britain…

  1. Eek – even the word makes me think of Victorian Gothic murder novels. Didn´t know what it looked like though, so very useful! Glad you found your way back safely….

  2. Luke Goudie says:

    the funny thing is, is that the toxin within hemlock dropwort is extremely similar to cowbane’s Cicutoxin, the only difference is one (yes one) double bond between the 15th and 16th carbon bond (right to left) This double bond is not present within the Cicutoxin and is within the Oenanthotoxin. and it is this subtle difference produce different symptoms and faster onset of symptoms/death makes cowbane slightly more toxic than hemlock dropwort (but rarer)

  3. Ashley May says:

    Waldron! I wish I’d read your blog before I went venturing in the New Forest last year! Whilst I didn’t consume any of the stuff, it took a life-saving slap in the face from my girlfriend to prevent me having a nibble of what my imaginative mind had construed to be some sort of abundant, riverside celery bush. I’ll try and pick up some more tips from your ace writings before I go out foraging again 🙂

    Hope you are doing well my man.

  4. Nick says:

    Thanks JP.
    A great article !
    Just discovered an abundance of HWD in a river near our sheep!
    Now need to work out how to dispose of it safely. Probably speak to environmental people.
    Thanks so much for the heads up.
    Nick Brown

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