Hansard

Like Mark Ruskell, I think that this is an interesting and important topic, given the £500 million of damage that is caused to the environment per year by the species in question. First, though, I thank Audrey Nicoll for bringing the debate to the chamber, not least because I have learned that Jackie Baillie is a defender of ancient woodlands. Her talents are extensive.

Invasive species are, as we know, introduced either directly or indirectly by man. Trade, transport, travel and tourism can move species around the world. Many species have been introduced intentionally for commercial purposes, such as for ornamental gardening, for farming or for forestry or as pets, only to escape and become established in the wild. Other species simply hitchhike, moving to new countries via people and transport. The most recent hitchhiker I can think of was a scorpion that had innocently taken shelter in a pair of trainers ordered online. The lesson is this: we should check inside our shoes, just in case. I once found a dead mouse in one of mine.

But I digress. It is easy for invaders to move around in a world of international trade, at both private level and commercial level, but I want to talk about plants. Plants or seeds that we buy from the garden centre will have undergone tests and certification that are pretty stringent and which have become even more stringent since our leaving the European Union. Before, there would have been, as I understand it, one biosecurity certification at the point of departure; now there is one from the EU export source, one on arrival in the UK and another at the wholesaler. That all comes with additional costs, which are all passed on to the consumer.

The issue was raised at a recent meeting of the cross-party group on gardening and horticulture, of which I am a member. Indeed, a joint letter from the Fresh Produce Consortium and the Horticultural Trades Association called for a meeting with the UK Government over the continued problems that their members face when importing plants, including trees and cut flowers, under the current border system. Notwithstanding that, biosecurity is crucial, and it is endorsed by the HTA.

However, some plants have escaped in the past and are now invading. Some have already been mentioned, but I will repeat a couple of them. The notorious Japanese knotweed, which was once considered an ornamental garden plant, has become established in woodlands, on riverbanks and in coastal areas. Its dispersal is due to both deliberate and inadvertent human activity, as a result of which fragments of the aggressive root system get washed downstream, spread and propagate, changing the habitat structure of riverbanks and thereby impacting on biodiversity, ecosystem structure, conservation efforts and even salmon fisheries. I recall seeing the plant with more friendly eyes some decades ago as it flourished along the riverbank at the bottom of my garden, before we knew that it was up to mischief.

Rhododendron ponticum—the purple rhody—is another non-native garden escapee plant that has become established and has spread across large swathes of Scotland, overwhelming other plants and preventing natural woodland regeneration. Again, I can recall seeing that in my youth just a few decades ago, when it was thought to be really pretty. How times have changed—and it is not the first or last example of a plant moving from being admired to being despised.

Then there is the American skunk cabbage, which is, yes, skunk by name and skunk by nature. It is very smelly. Years ago, when I visited Dawyck botanic garden near Peebles, which is one of the Royal Botanic Garden Edinburgh’s gardens, I thought that the yellow flowers growing in the streams were stinky, although that could be overlooked, because they were beautiful, and I selected one from the gift shop. A few years later, the Royal Horticultural Society told me to destroy it.

I thank Audrey Nicoll for bringing the debate to the chamber. I have found the research engrossing as well as worrying. Grey squirrels are more infamous, through no fault of their own—we brought them in—but we must also consider seeds, plants and the wee beasties that travel on them.