THE POISON GARDEN website       

5th October 2012

Sometimes, the absent is as interesting as the present. I’ve written a number of times, this summer, about the proliferation of Heracleum mantegazzianum, giant hogweed, in Edinburgh and the mostly hysterical reactions to Jacobaea vulgaris (syn. Senecio jacobaea), common ragwort. So many times, in fact, that I’ll leave you to go to the plant pages and follow the links back to the blog rather than list them all, again.

It struck me a couple of days ago, however, that there is one plant I would have expected to write about in the summer but have not.

Before I get to that plant I wanted to comment on the extent of common ragwort this year. There can be no denying that there has been more flowering ragwort visible than in recent years but this has led to two wrong conclusions by the anti-ragwort brigade. A number of local newspapers and ‘horsey’ websites have said that this year’s weather conditions have suited common ragwort and resulted in its abundance.

It is true that conditions, this year, have assisted plants to fully mature and flower but, since Jacobaea vulgaris is a biennial plant, it is conditions last year that account for the additional germination of plants so that those higher numbers were available to flower. Any assessment of why there was so much common ragwort this year needs, therefore, to look to 2011 not 2012.

And the second wrong conclusion is that this year’s prevalence indicates that common ragwort is spreading. The most recent surveys have indicated that the long-term trend is for the extent of ragwort to be largely unchanged. It takes more than one unusual weather pattern to affect the development or otherwise of a plant’s spread.

Datura stramonium, jimsonweed

The plant I haven’t mentioned but would have expected to is Datura stramonium, jimsonweed.  Last summer 4th July 2011 I wrote about the number of newspaper stories talking up the threat from what, in the UK, is simply a weed that appears in many gardens, probably, as a result of seeds being spread by birds.

This year, however, there seem to have been no such stories. It would be easy to leap to the conclusion that the weather conditions said to be favouring common ragwort do not suit the thorn apple but there are other possibilities. It may be that people are learning from the previous stories and no longer react with horror when they find the plant growing in their garden. It may be that the media has had plenty to write about this year, with the Diamond Jubilee, Olympics and Paralympics, so ‘silly season’ stories have not been required to the same extent.

It is impossible to say and we’ll have to wait until next year to see if the headlines about ‘Arrow Poison’, ‘South American Invader’ and ‘Devil’s Weed’ return to fill the space taken up by positive stories this year.

As I started drafting this, I had in mind to write that I had heard nothing at all about the plant this year but then one of my Google Alerts took me to a story from Switzerland. A three-year old boy was taken to hospital after becoming distressed. His parents realised that the crying child had one extremely dilated pupil.

After a physical examination found no reason for the condition, the boy was carefully questioned and it was discovered that he had been touching a Datura stramonium plant in the garden and had rubbed his right eye immediately afterwards. The Datura genus is closely related to Atropa belladonna, deadly nightshade, and contains many of the same toxins.

This young boy discovered what Venetian ladies knew centuries ago, that the plant is capable of causing mydriasis, dilation of the pupils, just by contact.