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Pontifications on Poison

Being some ramblings on events associated with poisonous plants.

Wednesday 29th June 2011

‘I missed you on Sunday’ said a fellow swimmer, ‘I wanted you to have a look at a plant’. Usually, when this happens, it turns out that someone has suggested that the mysterious invader is cannabis. And, quite often, it is. In this case I’ll never know because the neighbour whose plant is was had pulled it out and destroyed it before my swimming friend saw me.

Cannabis sativa

It a strange part of human nature that honest people get very concerned about the possibility that they have inadvertently done something the law regards as dishonest. Realistically, there is never going to be a raid by a fully tooled up drugs squad because a resident of a quiet village has a single cannabis plant growing in the garden.

In any case, that single plant, probably, has little chance of adding to the world’s stock of psychoactive substances. To understand that we have to delve a little into the botany of cannabis. Now, I’m not a botanist and, even if I were, this is not the place to deal with all of the botany of the Cannabis genus. You could write a book about that. In fact, someone already has.

So this is a very simple guide to what Cannabis does and why and how it does it. There are a number of ways that plants reproduce but I’ll concentrate on the three most common. Some plants have flowers that contain both male and female sexual organs. This means that an insect, not always a bee, shuffling around the flower to feed or collect nectar, will transfer material from the male to the female and fertilise the plant. Such plants are hermaphrodites.

When a plant has both female and male flowers on the same plant it relies on the bee, or whoever, flitting around the plant and happening to go from a male to a female flower with sperm of its body. These plants can also be wind fertilised and are called ‘monecious’.

And then there are the plants where there is complete sexual separation and a male plant has to be within range of a female plant for pollination to occur. These plants are often wind pollinated. Plants in the Cannabis genus are wind-pollinated.

One way in which the cannabis plant helps this pollination process is by the female producing a sticky resin to increase the chance that male pollen passing on the wind will get trapped. I’ve written before that plants want to reproduce and they will go to extraordinary lengths to help that to happen. In the case of cannabis, the female keeps producing resin until pollination has occurred. If no male pollen happens to pass by, the female will up the amount of resin to increase the stickiness of the plant. It just happens that this resin contains the highest concentrations of the psychoactive substances.

Cannabis sativa

I wrote ‘It just happens’ quite intentionally. A lot of plant folklore is based on the view that the human race is at the centre of everything and the appearance and actions of other life forms can be explained in terms of their relationship to humans. The whole ‘Doctrine of Signatures’ is based on the premise that the plants are telling us how to use them by the appearance they take on. That idea has, of course, faded from our reasoning but there are still people who subscribe to it.

Cannabis produces a sticky resin because it needs to do so to help it get pollinated. It happens that this resin contains substances that cause intoxication in humans. I have, however, read one supposed expert in cannabis who says that the plant produces psychoactive substances in order to make itself attractive to humans so that we will grow more of it and the plant becomes more successful.

Now, these substances are found in other places than the resin and do occur in the male plant but in much smaller amounts than in the flowers of the female. Anyone seriously interested in producing usable cannabis makes sure that they grow female plants and takes every care to ensure that pollination does not occur. Growing cannabis indoors, in the UK, does more than keep it out of sight and enable it to be grown much more quickly with artificial heat and light. It keeps the plants away from male pollen that could completely destroy the value of the plant.

A plant just coming up in the garden, usually as a result of birdseed or, in one incident I heard of from fishing groundbait, has a 50/50 chance of being male. And, even if it is female, it is not growing in conditions suitable for large scale resin production.

Plus, it may get pollinated by a nearby male.

At the Alnwick Garden, new Cannabis sativa plants were grown from seed each year. The gardeners would remove and destroy any male plants long before they reached maturity and, at the end of May, one unfertilised female plant would be put out in the Poison Garden. Normally, this would result in a very impressive specimen covered in flowers and full of resin and worth, I was assured, several hundred pounds by the peak visitor month of August.

One year, however, the plant didn’t seem to be going the usual way. It was healthy enough and was adding height as expected by the flowers were just not happening. One of the gardeners, something of an expert on the subject but we never asked how he came by his expertise, looked closely and quickly diagnosed that the plant had been fertilised and had ‘switched off’ resin production as a result.

Somewhere within wind travel distance of the Poison Garden someone had a mature male cannabis plant in their garden. So, they don’t all get pulled out at the slightest suspicion.