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Pontifications on Poison

Being some ramblings on events associated with poisonous plants.

Wednesday 28th December 2011 

Though I’ve said that I don’t agree with Thomas Hood’s poem ‘November’ that the month is devoid of almost all life I do agree that, the further time moves away from the end of November, the more life seems to be returning to the garden and you realise the time is fast approaching to make decisions about any new plantings or structural changes.

For me, the main decision for this coming year will be whether to have another try at growing Vitex agnus-castus, the chaste tree. Soon after I started this blog, I made the point that my actual gardening skills are very limited and this was ably demonstrated by my experience over the past two years of trying to grow the Vitex agnus-castus.

I have a selection of specialist nurseries I use when I want to buy the sort of plants that most people wouldn’t consider having in the garden. From time to time, people contact me via this site asking to buy one of the plants featured and I always reply by sending them a list of the places I go to.

It was one of these specialist nurseries where, early in 2010, I bought a small chaste tree in a pot. I didn’t know what conditions it wanted and, in any event, I only had one place for it so that would have to do. It made reasonable progress during the summer of 2010 and, as I knew it would, shed its leaves in the autumn and settled down for winter.

Vitex agnus castus, the chaste tree

Vitex agnus-castus, the chaste tree

Maybe it was my mismanagement or maybe no-one could have kept a young plant alive through the very severe winter that saw temperatures staying below freezing for days on end but there was no sign of any leaves appearing by June 2011 and when I went to do the scratch test, where you scrape a little bark of a stem to see if it is green underneath, the whole top came away in my hand as what roots it had established in 2010 had died and rotted away.

Because I’m generally impatient what I want is a good size bush but I’m not sure I want to have another go at growing it knowing I’ll have to spend several years tending it before it reaches a decent size.

The interest in this plant centres around its folklore, its medicinal use and its similarity in appearance to another well-known plant.

Also known as monks’ pepper, Vitex agnus-castus, is said to produce seeds that monks would consume in order to suppress any libidinous desires that might divert them from their devotions and monastic duties. But this use can be dated to, at least, the ancient Greeks. In those days, many plants gained their medicinal reputations due to the Doctrine of Signatures but there is nothing about the look of the chaste tree to suggest its alleged anaphrodisiac properties.

But it is this effect that leads to its use in herbal remedies. The active principles, volatile oils, are said to stimulate the pituitary gland and increase the production of progesterone, one of the female hormones. A 2001 paper in the British Medical Journal found that Vitex agnus-castus was better than placebo in relieving symptoms of premenstrual syndrome but but the following year another paper reported that the herbal extract was, overall, very similar in effect to the currently prescribed pharmaceutical, fluoxetine, so ‘Agnus Castus’ remains a herbal remedy rather than entering mainstream medicine.  

Vitex agnus castus, the chaste tree

Vitex agnus-castus, the chaste tree

That is a key point about medical research. It is often said that you do randomised controlled trials to see whether a medication is working better than placebo and that is true if there is no existing treatment for a condition. Where a medicine is already in use then the trial needs to be done against that medication because the new substance is only justified if it is better than, safer than or cheaper than the existing treatment. With Vitex agnus castus, it seems, none of those is true. There are slight variations between agnus castus and fluoxetine but, it appears, the balance between mental and physical effects and problems with side effects comes down in favour of fluoxetine.

Its similarity is to the sort of plant that turns heads when it is seen growing in the garden; Cannabis sativa. If I can’t have cannabis in the garden then I would like to have a plant that some people think looks like it.

The answer, I suppose, is to see if I can get a fairly mature plant but that means finding a very special nursery in amongst the specialist nurseries who supply my sort of plant.