THE POISON GARDEN website        

John Robertson next to a Catha edulis plant

...because every garden is a poison garden.

The purpose of THE POISON GARDEN website is to provide insights, many of them amusing, into the human race's long relationship with substances which have the potential to cause great harm.

But, before going any further, it's important to understand that accidental plant poisoning is very unusual and only very rarely do people suffer serious harm. Death from accidental ingestion of a poisonous plant is exceptional unusual. Further down this page you will find some results from a study in Switzerland.

I'm John Robertson and The Poison Garden website originated from my role as the first Poison Garden Warden at the Alnwick Garden.

I was involved with the Poison Garden for over four years and researched the stories told during Poison Garden tours as well as verifying, as far as possible, information provided by visitors. As a member of the Society for the Study of Addiction, I try to follow all the latest developments in our understanding of the issues surrounding substance abuse both legal and illegal.

Though the Poison Garden website comes about because of the knowledge about poison plants I developed in order to perform my role as Poison Garden Warden at the Alnwick Garden, neither John Robertson nor this site is now in any way connected with Alnwick Garden Enterprises Ltd and/or The Alnwick Garden Trust.

While I was Poison Garden Warden about 200,000 people a year took guided tours around the Alnwick Garden Poison Garden. Many expressed disappointment that the tour can only give a small part of the facts, fantasies and old wives' tales known about these poison plants. It was in order to try and address this disappointment that I developed a number of talks about poison plants. Initially, these talks were given in the Alnwick Garden but demand from many organisations led to the talks being given outside. This programme of talks continues to expand and you can read more about them on the 'Talks about The Poison Garden website' page.

A bee feeds on monkshood

But, even talks lasting an hour can only scratch the surface of the subject, so for the first time, The Poison Garden website gives access to many more of those stories together with pictures of the plants and stories which could not be told while I was still employed by the Alnwick Garden.

Down the right-hand side of this page, you'll find the opening paragraphs from the main pages of the site to help you to decide how you want to proceed.

The 'A to Z of Poison Plants' page leads to the section giving information on nearly 80 different poison plants, what they do, what used to be believed about them and what is still thought of them today. This section is not intended to be an exhaustive guide to all poisonous plants and contains much information which is anecdotal. For a reference book on plants, in the UK, which might pose hazards to children, I recommend 'Poisonous Plants: a guide for parents and childcare providers'.

It's worth pointing out that poison plants cause far less harm than might be expected. In 'Accidental poisoning deaths in British children 1958-77' published by the British Medical Journal, Neil C Fraser reports on a total of 598 poisoning deaths of children under 10 years of age. In the period covered only three deaths were attributed to plants. Even this low number is overstated since one death was due to fungi and in one of the other two 'the role of ingestion in the child's demise is doubtful'. Thus there may have been only one confirmed plant death, with 'hemlock' being the plant responsible, in twenty years. Fraser's analysis makes it clear that medication, household cleaning materials and cosmetics pose a much higher risk than poison plants.

Further evidence of the limited harm caused by plants comes from a 1996 paper  by Jaspersen-Schib et al and published by the Swiss Journal of Medicine entitled ‘Serious plant poisonings in Switzerland 1966-1994. Case analysis from the Swiss Toxicology Information Center’ (STIC)  

The researchers looked at 24,950 cases of contact with or ingestion of toxic plant material reported to the STIC. Severe plant poisonings occurred in only 152 cases (0.6% of the total) and sufficient details were available for 135 cases to be analysed. These cases involved 112 adults and 23 children and included 5 adult deaths.  

[It would be wrong to assume that a country as small as Switzerland and with its particular geography could be typical of the whole world but it does seem to be broadly similar to the USA where, in 2008, of 63,362 reported poisonings only 67 (0.1% of the total) produced a ‘major’ outcome with a further 1,252 (2.0%) having ‘moderate’ effects.]

Many of the old stories about the plants seem to us to be pretty silly. How foolish our ancestors were for believing that planting a particular plant near the house would guard against evil spirits.

How foolish our descendants will think we are for believing that the secret of a good night out is to snort a line or coke or drink huge amounts of alcohol.

In terms of number of cases, within the 135, there were eleven plants resulting in more than one case. These were;  

• Atropa belladonna, deadly nightshade, (42 cases)
• Heracleum mantegazzianum, giant hogweed, (18)
• Datura stramonium, jimsonweed, (17)
• Dieffenbachia, dumb cane, (11)
• Colchicum autumnale, naked ladies,(10 including 2 deaths)
• Veratrum album, sneezewort, (8)
• Aconitum napellus, monkshood, (4)
• Aesculus hippocastanum, horse chestnut, (3)
• Hyoscyamus niger, black henbane, (3)
• Oenanthe crocata, hemlock water dropwort, (2 including 1 death)
• Taxus baccata, yew, (2 including 1 death)  

The fifth fatal case was the result of the only reported incident of poisoning by Narcissus pseudonarcissus. This is the only case of fatal daffodil poisoning I have heard of and it resulted from inhalation of plant material which would, of course, have avoided the gastrointestinal upset that is usually found with daffodil ingestion and usually limits the effects of the toxins.  

Other plants involved in a single serious poisoning during the 29 years studied were Arum maculatum (cuckoopint), Asarum europaeum (wild ginger), Chrysanthemum vulgare (common tansy), Cyclamen persicum (cyclamen), Datura sauveolens (angels’ trumpet), Glycyrrhiza glabra (liquorice), Laburnum anagyroides (laburnum), Lycopodium (clubmoss), Nerium oleander (oleander), Senecio vulgaris (groundsel) and Vicia faba (broad bean).  

That the most common (albeit extremely rare) cause of serious poisoning, deadly nightshade, did not result in any fatalities suggests that its danger if often over-stated. That giant hogweed ranks second as a cause of serious harm is an answer to those who say that concern about Heracleum mantegazzianum is overblown and that there are many more dangerous plants around.