On 22/10/19 12:49, Nick Maclaren wrote:
In article ,
Martin Brown wrote:

When I visited the Poison Garden at Alnwick Castle there was one plant
that I couldn't abide being near. Henbane aka Hyoscamus niger. I could
smell the toxin in the air from its flowers and it was unpleasant.
(better than toothache I suppose if you were desperate)

http://www.thepoisongarden.co.uk/ato...amus_niger.htm

At least with Daturas and Brugsmanias the flowers usually smell gorgeous
even if the bruised stems smell terrible.

It had been a bad wet summer so several of the more interesting
semitropical specimens were dead mouldering brown stems. Best visited in
late summer after a long warm spell to see the most developed plants.

Gloriosa doesn't smell significantly, but it is SERIOUSLY poisonous,
much worse than anything that is naturalised in the UK, and I didn't
know if a single leaf or flower could kill a child.

I've grown it for years, and have never detected any scent. All the
reports of poisoning I've read about have followed ingestion of the
rhizomes. There are many comments about all parts of it being toxic, but
I haven't been able to find details of the levels of colchicine in the
leaves.

I don't understand your comment about it being "much worse than anything
naturalised in the UK". If we try to compare like with like, then surely
we should be comparing it with anything growable in the UK, even in a
tropical house. That opens the field to many very poisonous plants. But
even if limited to those which can grow and survive outside in the UK,
what about Colchicum?! It's exactly the same as far as possible
poisoning is concerned, with the same active principle. We can also
include other plants such as Aconitum, Veratrum, Convallaria, Digitalis,
and others with cardiac glycosides. If we include other classes, we come
to Ricinus and other polypeptide poisons (including Abrus if we return
to tropical plants). So the field is pretty wide. Perhaps the unique
thing about colchicine is that, as far as I am aware, in it's mode of
action it is in a class of its own.

The main UK problem comes from contact poisons getting in eyes or on
sensitive skin, but we have nothing compared to the manchineel.

But that is tropical too. Perhaps the best comparison with something
that /could/ grow in the UK would be the plants which contain urushiol;
those are the North American "Poison" plants - oak, ivy, and sumac. If
you want to consider other very nasty touch-sensitive tropical plants
you needn't look further than Dendrocnide moroides.

--

Jeff