skip to Main Content

The UK’s Most Poisonous Plants

Would you recognise the potential danger of some UK plants? Instant Scenery highlight the 5 most poisonous species that you are likely to encounter within the UK.

With the height of the summer now on us, people are out and about enjoying the weather. Whilst this is undoubtedly a wonderful thing for families to do, it is important to realise that some things in the garden or amongst the untended verge can actually be quite dangerous. In this article, Instant Scenery offer up what we believe are the five most commonly encountered and dangerous plants in the UK.

The Giant Hogweed.

Whilst this is certainly not the most poisonous plant on the list, it is most certainly worthy of a high profile note due to its occurrence. As a gardener I cannot justify ‘hating’ any plants – everything in nature fills a niche that we humans have done much to provide, but if I did have to voice a dislike of a plant, then Giant Hogweed would be near the top of the list. Firstly, it grows in awkward places. In my experience, I’ve found it on the edges of ponds and railway lines and canals that aren’t particularly easy to get to. Secondly is that they require careful ‘execution’ in order to avoid letting their numerous seeds escape to populate the countryside next year. Thirdly, when you do attempt to remove it, you need to be covered in protective gear to stop any of the sap getting onto your skin when you come to ‘wield the axe.’

The Giant Hogweed was originally introduced to Britain in the 1800s from the Caucasus Mountains (seeds were supplied to Kew Gardens by the Russian Botanical Gardens in 1817). Since then, it is now present throughout the British Isles.

The great danger of Giant Hogweed comes from its sap. Every summer the news includes stories of how families on their day out have had to visit a hospital because of the severe burns that these plants can cause. It is in fact a photo-toxin: so in sunlight the sap will react and burn the skin, often leaving scars that last for years. Indeed, as I write this, a cursory search on Google reveals a story in the Daily Mirror, of how a 16 year old girl was hospitalised after brushing against a Giant Hogweed specimen in her search for Pokemon Go.

Recognising Giant Hogweed is relatively easy if you know what to look for: it is essentially very similar to Cow Parsley, but the stalk contains purple blotches. The sap can even blind people if they get it in their eyes.

2. Monkshood and Wolfsbane (The Aconite family).

In the UK, Monkshood is perhaps the most poisonous plant that grows natively. This is instantly recognisable due to its purple hanging flowers, in the shape of a monk’s habit. Both touching the leaves, and (more so) eating them, can lead to severe and possibly fatal poisonings. The sap too is also poisonous. In fact, the name of the other well-known aconite, Wolfsbane, was given to it due to the legends of baited meat being poisoned with the ground roots of the flower to kill marauding lupines.

Aconite has also (but very rarely) been used as a murder weapon: one of note was the ‘curry killer’ in 2009 who was convicted of using Indian Aconite to poison her ex-lover, hiding the taste by mixing it in with the curry. The victim died within an hour of arriving at hospital, though another dinner companion was placed in a medically-induced coma and was reported to have made a full recovery. (The previous case in the UK of someone using aconite as a murder weapon was back in 1882!)

3. Hemlock. (Poison Hemlock).

This is a well-known poisonous plant thanks to the execution of Socrates 400 years before the time of Christ, who was condemned to death by Athens and was made to drink the hemlock in a tea. (Though according to some Christian traditions, Hemlock only became poisonous after growing on the hillside of Jesus’s crucifixion!)

The Hemlock family actually includes a number of plants, but in the context of this article, with its focus on the UK, I am referring to Poison Hemlock. The key reason this is such a danger is that it is so easily confused with Cow Parsley, which is a favourite of foragers. There is a wonderful video, by Robin Harford from the Eat Weeds website, which seeks to educate viewers on the differences between them: they really are quite similar. Have a look at it and see if you can spot the difference:

4. Belladonna / Deadly Nightshade.

Deadly Nightshade was the fearful plant of my childhood that I first learned as being poisonous, with both foliage and berries being extremely toxic. Not only is its name so brilliantly evocative, but it has historical uses that seemed to mark it out as a particularly nasty toxin (or, if I am being more accurate, it was used by nasty people to do some nasty things!)

Any fan of Roman drama and history will no doubt have seen the wonderful ‘I, Claudius,’ by Robert Graves, featuring a young Derek Jacobi in the leading role as the thoughtful though stuttering historian turned unwilling emperor due to his family’s machinations. Well, Deadly Nightshade had more than a cameo part in the true life drama: it was reputedly used to poison the emperor Augustus, (his wife poisoned her own food and then offered these to him, knowing he would not accept any other food from anyone else). Even Macbeth (that Macbeth!) is supposed to have used it to incapacitate a whole English army, slipping it into their food or drink during a truce, after which they retreated back to their ships feeling unwell (although I am not sure if I believe that latter one – it would have taken a lot of Deadly Nightshade to upset an army, yet alone the logistical difficulties of administering it to all their food in enough quantities for it to work).

The other name for Deadly Nightshade is, of course, Bella Donna, which in Italian means ‘Beautiful Lady.’ This name comes about due to one of the plants other uses as a cosmetic that was known in the ancient world: the herb was used in eye-drops to dilate the pupils to make women appear more attractive. It just goes to show how resourceful our ancestors were in making use of nature’s bounty.

5. Foxglove.

This plant is probably the most well-known example of the fact that some poisons also have, in the right doses, applicable treatments. Foxgloves are famed for the digitalis that is found in the entire plant (leaves, flowers, roots, stalks and seeds), and yet this digitalis is used for controlling pulse rates in patients with heart conditions since its discovery by William Withering in 1785.

Digitalis was also a favourite of Agatha Christie’s in her many novels, such as Appointment with Death, or Thirteen Problems, so it has entered cultural mythology. And it might also have played a prominent role in one of the twentieth century’s greatest artists: Vincent Van Gough’s yellow period might have been influenced by his digitalis medication that he took to control his seizures – a symptom of which is seeing halos around objects.

Whilst the flowers of the plant are instantly recognisable, care must be taken with regard to the leaves, which are similar to Doc leaves in appearance although of a different texture (appearing furry). There is a very touching account of an accidental poisoning of a two year old girl in Wales recently, which very fortunately had a happy ending. It is well worth a read and acts as a very sobering human interest story in contrast to my brief foray into the plant – I have copied the link in below.

Esme’s Adventure with Foxgloves

Whilst poisonings from flowers are very rare, and more often accidental than deliberate, it is no doubt interesting and wise to have some knowledge of them and what they can do. We live in a world isolated from nature, some of us spending more time in virtual realities than the real one, and the lack of knowledge that I see in some people who have little time to interact with nature is, I find, both dangerous and frustrating. As a landscape gardener with an interest in nature, I feel it is my duty to fight this battle, and I hope that this article can inspire you to research the plants in your own vicinity and to appreciate their potency that much more.

Sign up to our newsletter for the latest gardening news


Instant Scenery: 3 Paddock Close, Kempsey, Worcester, WR5 3WE  Call: 01905 347105  Email:

Copyright Instant Scenery 2020 - All Rights Reserved - Website By: Dazzle Creative

Copyright Instant Scenery 2020 - All Rights Reserved - Website By: Dazzle Creative

Back To Top