In conversation with Anna Perks, Falkirk Council’s lively Bio-diversity Officer, at the recent Falkirk District Flower Show, I jokingly remarked that it would not surprise me to learn that some less-than-wholly-clued-up gardeners were actually known to give cuttings of ‘this lovely plant that has just appeared in our garden’ to friends and neighbours, the ‘lovely plant’ to which I was referring being Himalayan Balsam, botanically known as Impatiens glandulifera, which, to be fair, is a not unattractive plant. And Anna reminded me that Himalayan Balsam was indeed first introduced into the United Kingdom as a garden plant in the early nineteenth century, brought here from the west and central Himalayas in good faith by plant collectors who thought, rightly, that it would do well in these islands.
How right they were! The first recorded sighting of Himalayan Balsam growing in the wild in England is dated 1855, though it had probably ‘escaped’ from gardens before that date - and the proper term for an imported plant that moves out of gardens and into the wild is ‘escaped’. Nor, of course, will this surprise anyone who knows that Impatiens gets its botanical names from the impatient way in which it scatters its seeds, the seed pods exploding - in the manner of broom - to scatter the lightweight seeds for the wind to carry who-knows-where.
No problem, one might suppose, for a great many attractive plants which were first imported as garden species have escaped to the wild and are a welcome addition to our natural flora. But Impatiens glandulifera has proved to be a most unwelcome addition to the diversity of our population of natural plants; for Impatiens glandulifera out-muscles native plants, particularly along river banks and in damp woodlands - indeed, in almost any rather damp habitat, forming densely packed areas of growth and choking out smaller and less aggressive natural species. Worse still, Impatiens glandulifera leaves large bare areas of soil when it dies back in the winter, bare areas which, when they are on the banks of rivers and streams, can allow the winter waters to erode their banks, which can lead to flooding. Not nice!
And believe it or not, there are still some people who deliberately plant Himalayan Balsam in their gardens for, although it is an offence in England and Wales to plant Himalayan Balsam in uncultivated ground or allow it to spread from a garden into the wild … how do you stop it, I wonder? … it is not an offence to sell the plant nor an offence to plant it in an English or Welsh garden. We are either more tolerant or more realistic north of the border where, though planting the stuff is strongly discouraged, there’s no illegality about it.
So how do you recognise this unwanted plant? First of all, it’s tall, growing up to two metres in height - say just over six feet in old money. In the Spring, the new stems change from green to red, a colour that they then keep throughout the Summer, with long, bright green leaves up to fifteen centimetres long - six inches for everyone who still thinks in feet and inches. The pink, sweetly-scented flowers are trumpet-shaped and actually quite attractive; and these mature into seed pods not unlike small pods of garden peas but only about two-and-a-half centimetres, or one inch,. in length These pods explode in the Autumn to scatter their small seeds to the wind. And if a friend offers you either a clump of plants or a small envelope of their seed, just say no and suggest they visit www.nonnativespecies.org to learn more about this unwelcome immigrant. In fact, we might all be well advised to visit this website to learn more about some of the plants brought to this country in good faith but now creating real problems in the countryside.
Sandy Simpson, Polmont Horticultural Society