The UK’s most poisonous plant
By Jennifer Holmes

The UK’s most poisonous plant

The deadly Hemlock Water Dropwort (Oenanthe crocata)

According to the Environment Agency (EA) July 2022 saw just 10% of its long-term average (LTA) rainfall across England, and we’re almost certainly heading into an August drought if these conditions remain. Reduced rainfall affects rivers and aquatic ecosystems with the lack of river flow causing riverbanks to recede, resulting in many underground rhizome plants being exposed.

One such plant is the invasive species known as Dead Man’s Fingers – named due to the rhizomes appearing finger-like when emerging from the ground. News recently surfaced that the UK’s most poisonous plant was found by a canal in Chorley. Hemlock Water Dropwort – its official name is extremely toxic to humans and wildlife, death can apparently occur in a few hours after eating it.

A weed by any other name

Dead Man’s Fingers and Dead Tongue are just a few of the names for Hemlock Water Dropwort. Hemlock Water Dropwort is an extremely poisonous perennial plant that is a member of the carrot family. Despite being one of the UK’s most poisonous plants, it has a very sweet and pleasant scent.

According to Wild Food UK “The root is said to taste like parsnip before poisoning the consumer.”

Dropwort’s habitat

Dropwort likes a moist environment and can be found growing naturally in damp meadows, near ditches, ponds, lakes and other bodies of water.

Dropwort characteristics

One of the issues with plants like Hemlock Water Dropwort is its family resemblance to much less harmful relatives such as Flat Leaved Parsley, Water Parsnip or Water Celery. This can make identification a little tricky, and often its mistaken identity results in poisoning.

Here are some characteristics to look out for:

  • Bright green and shiny leaves that form a triangular shape with two-to-four pinnate divisions.
  • Shiny hollow stems that can grow up to 2m tall
  • Small white flowers that grow in clusters
  • Brown rugby-shaped seeds that follow the flowers and form up clusters

What happens if you ingest Hemlock Water Dropwort

There is a reason that this plant has names like “Dead Man’s Fingers” – it’s the most poisonous plant in the UK. Death can apparently occur in a few hours after eating it. All parts of the plant contain toxic alkaloids that can be fatal, even in small amounts. The toxic alkaloids can affect nerve impulse to the muscles and eventually kill through respiratory failure.

Hemlock in History

The toxic alkaloids that affect the nerves cause the muscles to contract leaving an ‘eerie smile’ frozen on the face of the corpse – the “Sardonic grin” that Homer refers to. The plant was used in pre-roman times on elderly people that were no-longer able to support themselves.

The term for the bitter and cynical grin known as a “Sardonic smile” has dark origins. It comes from the Greek poet, Homer who was said to have coined the phrase a millennia ago. Researchers in Italy discovered that the hemlock water-dropwort that grows wild across the island of Sardinia was used in ancient death rituals.

Getting rid of Dead Man’s Finger

So first and foremost, it goes without saying that dealing with this plant presents a risk – and should not be handled.

We would always recommend that you start out with a survey and hire in professionals (like us) to deal with toxic, poisonous and invasive weeds. Not only because it’s our business, but because this way you can ensure that everything is being handled safely, effectively and importantly; disposed of properly.

We have the tools, equipment, knowledge and experience to get it done right and get it done safely so that you don’t need to put yourself at risk.

Wrapping up

So, there you have it. Dead Man’s Fingers – the UK’s most poisonous plant. If you suspect that you have come across this, or any other invasive weeds that you might not be sure of, Japanese Knotweed Ltd offer a free identification service to help.

Just send along the location and some pictures to and our resident weed experts will identify it for you.