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.

Tuesday 27th September 2011

I’m working on a new page for the A to Z section about Rhododendron. (UPDATE; the page is now available here) It is not an especially poisonous plant, in fact, it isn’t included in the Horticultural Trades Association (HTA) list of potentially harmful plants. This is the list that forms the basis for Dr Elizabeth Dauncey’s book ‘Poisonous Plants – A guide for parents and childcare providers’.

But, it is poisonous and there is a particular situation with the nectar of the plant that leads to some of the exaggerated stories about the harm that is caused as so often happens with poisonous plants. My problem, so far, is that I’m not too sure how interesting it is.

The Rhododendron is a native of southern Europe all the way from Spain in the west to Turkey in the east. In those areas stories about the effects of the toxic nectar date back to about 400BC but it was unknown in the UK until the 18th century. John Gerard, for example, has no mention of it.


It is said that the first Rhododendron ponticum was introduced to the UK in 1763. Like a lot of non-natives, it took to its new home and soon began to colonise whole areas where just a few plants had been introduced. Today, you will often hear that Rhododendron ponticum is a serious problem but that is almost certainly untrue.

I don’t mean that large swathes of Rhododendron aren’t extremely troublesome. I mean it is very unlikely to be R. ponticum. Rhododendron is thought to appear in around 1,000 species and those species produce innumerable hybrids. This means there are very few people expert enough to identify exactly what Rhododendron a particular plant is.

In terms of appearance and flowering, that doesn’t matter too much but it has been found that the concentration of the main toxin is species/hybrid dependent so plants that appear to the layman to be identical may produce different degrees of poisoning.

In general, it is the toxic nectar that continues to attract most of the interest and the difficulty of distinguishing exactly which species or variety of Rhododendron is what leads to confusion between bee-keepers when they find that bees are dying from visiting Rhododendron bushes ‘exactly the same’ as other bushes that have produced no ill effects.

Of course, it is the question of whether toxic honey gets consumed by humans that is of most interest to the majority. It seems unlikely. First of all, as above, bee-keepers know that their bees are visiting Rhododendron when significant numbers die. Obviously, these dead bees don’t make it back to the hive to unload their toxic cargo. In areas where there can be high concentrations of flowering Rhododendrons, bee-keepers are reported to keep their hives closed until the danger passes.


Then there is the question of how bee-keeping works. Nectar collected early in the year, and Rhododendron are often the first bushes in flower, is often retained to feed the hive and it is not until later in the summer that honey is removed.

Then there are those who say that the toxin, variously called andromedotoxin, grayanotoxin, rhodotoxin and acetylandromedol, decays with time in honey so that by the time honey is consumed the level of toxicity is negligible. And honey with a high level of toxins from Rhododendron is said to be unpleasant to the taste though not, perhaps, as unpleasant as honey made exclusively from Jacobaea vulgaris, common ragwort, as there have been reported cases of honey poisoning.

So, there’s quite a bit of fact about the toxicity of Rhododendron and some of the claims made about the harm arising from honey belong in the fiction category. What I don’t have much of, so far, however, is folklore. Being such a newcomer to the UK it hasn’t developed any UK-based folklore and it doesn’t seem to have much in its native lands other than a vague notion that it is ‘protective’ against evil.

What started me thinking about creating a page was a news story, today, that the National Trust are close to completing a project to clear Brownsea Island in Dorset of Rhododendron in order to have a safe habitat for one of the few colonies of red squirrels to be found in England. We usually think of the grey squirrel as being the foreigner endangering the survival of the red. On Brownsea Island, however, the foreigner is a plant that more or less took over completely leaving no habitat for the red squirrel.  

It’s a stark lesson in the effects of invasive species to learn that the work on Brownsea has taken fifty years to complete.


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.