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Pontifications on Poison

Being some ramblings on events associated with poisonous plants.

Wednesday 19th October 2011

They’ve been digging up the road for what seems like months. Turn left out of our house and it is about three miles to the first crossroads. A couple of months ago, they began digging up the verge at that crossroads and heading in our direction.

Rumex obtusifolius, broad-leaved dock

Rumex obtusifolius, broad-leaved dock

‘They’ are contractors working for the water company and the boards assure us that they are ‘improving services’ with these works. What that means is they have dug a trench, almost entirely along what was a grass verge at the edge of the road, placed a large blue pipe into it and replaced the earth over it.

I’ve been watching to see how quickly plants, of any sort, have re-appeared in the disturbed soil left behind by the works. Though they only reached our village a couple of weeks ago, the verges up near the crossroads where they started are already pretty well covered with vegetation.

I haven’t stopped the car to make a detailed examination but it seems that the re-growth is mostly a mixture of grass, broad-leaved dock, and cow parsnip. Broad-leaved dock is Rumex obtusifolius and cow parsnip is Heracleum sphondylium. It may take until spring next year before we see if disturbing the soil has encouraged any long dormant seeds to germinate.

Papaver somniferum, opium poppy

Papaver somniferum, opium poppy

I don’t know why some plants need this kick start after remaining in the ground for prolonged periods. The best known example of plants that appear after ground has been disturbed is the Papaver genus or more specifically Papaver rhoeas, corn poppy. This was the species that appeared in abundance after the fighting in France during the First World War caused large scale disturbance of agricultural land. Papaver somniferum, opium poppy, also behaves this way and people are sometimes surprised when their garden is suddenly full of poppies years after they last grew them.

We’ll have to see if any poppies appear on our verges next spring but, before that, it will be interesting to see if the several patches of daffodils, Narcissus spp., that have colonised parts of the roadside have survived the upset.

As I noted, it is a couple of weeks since the main work on the verges was completed, though there are still small bits to be finished off and there is still plenty going on in the small waterworks up the road where the new pipes terminate. What made me write about it today was seeing an image posted on the Geograph website. If you’re not familiar with it, I’ll quote the home page by way of explanation; ‘The Geograph Britain and Ireland project aims to collect geographically representative photographs and information for every square kilometre of Great Britain and Ireland’.

Heracleum mantegazzianum, giant hogweed

Heracleum mantegazzianum, giant hogweed  

The image I saw was taken by and posted to the site by someone called Derek Harper who had, previously, as I discovered, posted a couple of images of work going on near Shiphay in Torbay to tarmac a stretch of bridle path. Today’s image, taken on 13th October, shows the first plant to appear through the bare earth at the side of the newly laid bridleway. That plant is Heracleum mantegazzianum, giant hogweed. Here’s the picture.

Now I was a little surprised to see giant hogweed this far south-west but another of Mr Harper’s photos  shows a mature plant from a nearby site photographed last July so it, clearly, is not a completely new arrival.

But I was even more surprised to find a plant that begins its growth cycle in March or April appearing in October. I’ve blogged before about the determination of a Heracleum mantegazzianum plant to produce seed 28th June so I shouldn’t be surprised at the determination being shown by this specimen. I shall have to try and contact Mr Harper to see what happens to the plants as the weather turns colder and the days shorten.