THE POISON GARDEN website      Arum maculatum berries on a Cannabis leaf 


This free script provided by JavaScript Kit

Pontifications on Poison

Being some ramblings on events associated with poisonous plants.

Thursday 30th June 2011

At last, for those of us further to the north of the UK, there has been a bit more warmth and even some sunshine resulting in more flowers opening and more activity from the bees and other pollinating insects.

As a child, I used to accept it when I was told that bees pollinated flowers and made honey with the nectar they collected. As a city boy, I didn’t distinguish between honey bees and bumble bees. They were all just bees. But, it turns out, it’s a bit more complicated than that and so is the answer to the question ‘Why don’t bees get poisoned?’

Papaver somniferum, opium poppy

Now I know that not only are there lots of different species of bees, even though I haven’t made a huge effort to learn how to identify them, but that many other insects play a role in plant pollination.

The Viburnum* that we planted, ten years ago, from a cutting taken on our one-day gardening course, is now a substantial shrub and has been literally buzzing with wasps for a few weeks now. And my Papaver somniferum, opium poppies, are usually a strong attraction for marmalade hover flies, especially the peony flowering varieties. Plus, of course, there are quite a few plants, in addition to the dramatic Dracunculus vulgaris, dragon arum, that rely on flies to do the business for them.

I don’t know what relative contributions to total pollination these different insects make but I do know that there is more to it than the headlines we keep seeing that, if the honey bees’ problem isn’t dealt with, we’re facing a calamity. Though I can’t name them, I would say I’ve seen at least five different species of bee in the garden so far this year though many people, I suspect, would assume they were all honey bees and all, therefore, at risk.

Dracunculus vulgaris, dragon arum

At this point, I should find myself guilty of the crime I frequently find in others. If we were to use the zoological names for these insects there could be no confusion. Saying that problems are occurring for Apis mellifera, which is the specific species kept for honey production and subject to so-called colony collapse disorder, avoids any confusion with the up to 43 other species and sub-species of honey bees.

But, back to the original question, with the revision that it should be ‘Why don’t pollinating insects get poisoned?’ and adding the important second question, ‘Can poisonous honey be produced?’ because, though people are more likely to be concerned about the wider world these days, they are much more interested in knowing if they are taking a risk by putting honey on their toast.

There are a number of answers. First, there is the question of dose, as there always is with poisons. Pollinating insects, or rather I’ll stick to bees as they are the creatures who make honey consumed by humans, usually visit hundreds of different plants in the course of a day. Those plants can be different genera or different varieties of the same species but they ensure that the bees are collecting only a tiny amount of any toxins that might be found in the pollen and nectar they take back to the hive. There is very little chance that, if you directly collected all the material from one bee, it would contain a high enough proportion of toxins to be a potential poison.

There are exceptions of course and these arise when one plant is dominant in a particular area. In the north-west of Scotland, huge numbers of Rhododendron ponticum are the only flowering plant at a certain time in the spring. It is known for bees to die after visiting this one species during a day’s work. Commercial bee-keepers, and informed amateurs, know this and will keep their hives closed for this period. Since, in this case, the toxins in the plant are sufficient to kill the bees we can assume that they don’t manage to produce toxic honey.

Senecio jacobaea, ragwort

Of course, we can’t be sure that the toxins in a plant survive the process of being converted from nectar to honey. Some do, as we’ll see in a moment, but it may be that the manufacturing process changes the chemicals so as to reduce their toxicity.

The other plant that can dominate an area is Senecio jacobaea, ragwort, and there was sufficient concern about this possibility for the UK’s Ministry of Agriculture to conduct trials. In short, the work did find examples of honey containing potentially harmful concentrations of the pyrrolizidine alkaloids that make ragwort hepatotoxic but, and this is key, those samples were very dark in colour, foul-smelling and totally inedible.  

The only occurrence I know of where poisonous honey has been consumed resulting in harm to humans is the Coriaria arborea, tutu, found in New Zealand, but here the mechanism for the production of the honey is unusual. Bees collecting nectar directly from the plant do not produce poisonous honey. But, a vine hopper insect also feeds on the nectar of the plant and excretes a sweet ‘honeydew’ containing a high concentration of plant toxins. Especially in times of drought, bees may gather this honeydew rather than nectar from the plants. Because this is a well-known problem, however, there have been no instances of poisoning from commercially produced honey since 1974.

When four people were taken ill in 2008, the source was traced to honey produced by an amateur who was not aware of the problem. Another instance of the flaw in the belief that the more ‘natural’ something is the better it is for you.

*It turns out that the Viburnum is actually Cotoneaster lacteus. Another example of the true extent of my gardening knowledge. (Added 19th August 2013.)


Full Entries


Tuesday 25th October 2016
Saturday 20th August 2016
Sunday 6th March 2016
Wednesday 3rd February 2016


Saturday 28th November 2015
Friday 27th November 2015
Monday 17th August 2015
Wednesday 15th July 2015
Friday 26th June 2015
Thursday 25th June 2015
Thursday 30th April 2015
Wednesday 29th April 2015
Wednesday 11th March 2015
Tuesday 3rd March 2015
Saturday 28th February 2015
Sunday 22nd February 2015

November 2014

Monday 24th November 2014
Saturday 8th November 2014

October 2014

September 2014

Wednesday 24th September 2014
Monday 1st September 2014

August 2014

Tuesday 26th August 2014
Saturday 16th August 2014
Tuesday 5th August 2014
Friday 1st August 2014

July 2014

Sunday 27th July 2014
Wednesday 23rd July 2014
Sunday 13th July 2014
Sunday 6th July 2014
Tuesday 1st July 2014

June 2014

Wednesday 25th June 2014
Tuesday 24th June 2014
Sunday 22nd June 2014
Monday 9th June 2014
Wednesday 4th June 2014

May 2014

Monday 26th May 2014
Sunday 18th May 2014
Wednesday 14th May 2014

April 2014

Sunday 13th April 2014
Saturday 5th April 2014
Thursday 3rd April 2014
Tuesday 1st April 2014

March 2014

Monday 31st March 2014
Tuesday 25th March 2014
Friday 21st March 2014
Monday 17th March 2014
Sunday 16th March 2014
Tuesday 11th March 2014
Tuesday 11th March 2014
Thursday 6th March 2014
Wednesday 5th March 2014
Saturday 1st March 2014

February 2014

Thursday 27th February 2014
Monday 24th February 2014
Wednesday 19th February 2014
Monday 17th February 2014
Thursday 13th February 2014
Monday 4th February 2014
Monday 3rd February 2014
Saturday 1st February 2014

January 2014

Thursday 28th January 2014
Thursday 23rd January 2014
Friday 17th January 2014
Wednesday 15th January 2014
Monday 13th January 2014
Thursday 9th January 2014
Tuesday 7th January 2014
Wednesday 1st January 2014

December 2013

Monday 23rd December 2013
Friday 20th December 2013
Tuesday 17th December 2013
Friday 14th December 2013
Thursday 12th December 2013
Sunday 8th December 2013
Wednesday 4th December 2013
Sunday 1st December 2013

November 2013

Friday 29th November 2013
Wednesday 27th November 2013
Tuesday 26th November 2013
Friday 22nd November 2013
Monday 18th November 2013
Friday 15th November 2013
Thursday 14th November 2013
Sunday 10th November 2013
Thursday 7th November 2013
Wednesday 6th November 2013
Friday 1st November 2013

October 2013

Thursday 31st October 2013
Sunday 27th October 2013
Wednesday 23rd October 2013
Monday 21st October 2013
Friday 18th October 2013
Friday 11th October 2013
Wednesday 9th October 2013
Tuesday 8th October 2013
Monday 7th October 2013
Tuesday 1st October 2013

September 2013

Monday 30th September 2013
Saturday 28th September 2013
Friday 27th September 2013
Monday 23rd September 2013
Sunday 15th September 2013
Monday 9th September 2013
Tuesday 3rd September 2013
Sunday 1st September 2013

August 2013

Sunday 8th September 2013
Tuesday 3rd September 2013
Sunday 1st September 2013

Tuesday 27th August 2013
Sunday 25th August 2013
Monday 19th August 2013
Friday 16th August 2013
Tuesday 13th August 2013
Friday 9th August 2013
Friday 2nd August 2013
Thursday 1st August 2013

July 2013

Saturday 27th July 2013
Sunday 21st July 2013
Wednesday 17th July 2013
Monday 15th July 2013
Saturday 13th July 2013
Friday 12th July 2013
Thursday 11th July 2013
Wednesday 10th July 2013
Tuesday 9th July 2013
Saturday 6th July 2013

June 2013

Friday 28th June 2013
Tuesday 25th June 2013
Friday 21st June 2013
Thursday 20th June 2013
Wednesday 19th June 2013
Saturday 15th June 2013
Sunday 9th June 2013
Saturday 8th June 2013
Saturday 1st June 2013

May 2013

April 2013

March 2013

February 2013

January 2013

December 2012

November 2012

October 2012

September 2012

August 2012

July 2012 blog

June 2012 blog

May 2012 blog

April 2012 blog

March 2012 blog

February 2012 blog

January 2012 blog

December 2011 blog

November 2011 blog

October 2011 blog

September 2011 blog

August 2011 blog

July 2011 blog

June 2011 blog


The POISON GARDEN website is not connected with Alnwick Garden Enterprises Ltd and/or The Alnwick Garden Trust.