Return of the giant hogweed

'Turn and run! Nothing can stop them. Around every river and canal their power is growing.' Funny, but it has never occurred to me before now that Peter Gabriel's apocalyptic, if rather fanciful, lyrics to The Return of the Giant Hogweed (Nursery Cryme 1971) are about the true story of the introduction of the plant to the Botanic Gardens at Kew during the great age of Victorian acquisitiveness, and its inevitable consequences. In Gabriel's re-telling the giant hogweeds take on the guise of John Wyndham's triffids, bent on vengeful human annihilation.

Giant hogweed by the river Esk

Last week I was writing about our harmless native hogweed. Today, walking the river Esk in East Lothian, I came across an immense infestation of giant hogweed, Heracleum mantegazzianum, an altogether more frightening encounter. There were many specimens of easily twice my height and the large area, completely overrun by the plant, was sealed off behind barbed wire. And for good reason... giant hogweed is best given a wide berth.

The plant produces a sap which reacts with ultraviolet light. Even mild contact such as brushing against the hairy stems can leave the skin hyper-sensitive to sunlight, resulting in painful and persistent blistering that may recur for years. The giant stems are hollow, making them attractive for children's games as swords, blowpipes or telescopes, with potentially horrible consequences. There are cases of hospitalisation every year.

As Peter Gabriel laments, giant hogweed, which originates from the Russian Caucasus, is virtually indestructible, requiring a co-ordinated effort by landowners, local authorities and environment agencies over a many years. According to East Lothian Council's website, council officers are engaged in a long-term campaign of eradication, backed by legislation making it an offence to plant giant hogweed or to allow it to grow unchecked on private land.

Sandra has written recently about the tenacity of weeds and the futility of our attempts to submit them to our will. Readers of my earlier posts will know that I, too, am an admirer of the weed. I am left with a sense of deep ambivalence about plants like the giant hogweed and Himalayan balsam and others. After all, we reap what we sow. Brought to Britain as ornamental curiosities, they are one legacy of the colonial hubris of our ancestors. In spite of all our best (and costly) efforts at eradication they are almost certainly here to stay. Containment through responsible environmental management is probably the best we can hope for.

Let me stress I have absolutely no wish to see children blinded or disfigured through contact with this plant, any more than I would want to see people bitten by adders, poisoned by mushrooms or injured by any other agent of our natural world. In that sense we are fortunate in Britain that there is not much out there to do us serious harm. But in our enlightened twenty-first century do we still entertain the eradication of species on the grounds that they are potentially harmful to us, our pets or our livestock? What is missing from East Lothian Council's website is surely what should be the second prong of its campaign, education. There are no photographs or drawings by which to identify the plant, no advice for parents or gardeners on avoiding contact or what to do if experiencing symptoms. We must kill it, that is all.

The giant hogweed is undoubtedly impressive although not especially attractive. It is certainly a plant to be treated with extreme caution. On balance it would probably have been better if Victorian gentlemen collectors had not brought it here. But they did and we must learn to live with it as we must the grey squirrel, the sycamore, the mink, the rhododendron, the New Zealand flatworm and the myriad other newcomers to our islands. We should remember that unlike John Wyndham's sci-fi triffid, the giant hogweed isn't an invader, we introduced it.