The subject of weeds is one which is seldom too far from the forefront of the gardener’s mind.
Weeds come in many shapes and forms and are very personal; for a weed is a plant which seeks to establish itself in an area where the gardener does not wish it to be. Thus a plant which is highly-prized by one horticulturist may well be a weed to another. And, of course, weeds are spread by many agencies - by spreading roots, by seed eaten by birds and deposited in their droppings, by seed carried by the wind, by water, by human agencies (usually inadvertently) and by being delivered in the soil of a bought plant. Yes indeed, the means of their transmission are many and varied.
Obviously, some of these means of transmission are more suited to short journeys … spreading by underground root systems or by ingestion by birds, for example … while others can take a plant many miles … wind dispersal or spreading by human agency, to name a couple. And it is the former … short-distance transmission … which is in the forefront of my mind, for I have recently realised that there has been an intriguing change over the years in the nature of the most prevalent weeds in my garden in Polmont.
When we moved into our home alongside the Edinburgh and Glasgow railway line forty-plus years ago, the railway embankment behind the house was home to as impressive an orchard of bramble bushes as one could ever hope to find. Come the autumn, and the birds which feasted on the luscious berries deposited the seed most generously in our garden and in the gardens of our neighbours. It took only a tiny proportion of the seed to germinate and take root, and by the following spring young bramble bushes seemed to be springing up absolutely everywhere. And Mother Nature seemed to take pity on us, for she co-operated very willingly in bringing about a huge reduction in the number of railway-owned bramble bushes. I sprayed a defoliant chemical on those which were readily-accessible from my side of the boundary wall; and Mother Nature in some mysterious way brought about the demise of many bushes far beyond the range of my sprayer.
But my joy was short-lived; for within a couple of years that dreaded plant known to me as horsetail had established itself big-time in the grasses which had replaced the brambles; and the roots of horsetail are very invasive and very persistent, creeping unseen under the boundary wall in a determined bid to enlarge the area under this noxious weed’s control. Spraying is of limited use against horsetail, the foliage of which is pretty good at shedding droplets of liquid rather than ingesting them; and I turned the plant’s own dispersal system against it, laboriously injecting deadly chemicals into the root systems which then obligingly carried the killer liquid through the entire underground root network. Slow, tiresome work this undoubtedly was: but it was successful and in a couple of years the horsetail had been eliminated entirely from the banking behind the house and from my garden.
The next arrival was rosebay willowherb; it took a few years for this seed-dispersal-by-gossamer-parachute to grow in massed ranks. But appear it did; and thrive it assuredly did and, indeed, still does, despite my best endeavours. And this year it has been joined by what I can only describe as a plague of thistles. There were none of these, I am absolutely certain, two or three years ago; yet the Network Rail ground is now home to a carpet of them, happily thriving … and spreading … alongside the willowherb. Where have they come from? And why are these changes occurring in the dominant plant species? Mother Nature, please tell!