Snakes & Ladders – Painted quilt
Artist: Denise Furnish

Like weeds, when we talk about invasive species, we usually know which ones we mean. They’re the ones we don’t like.

So, when we talk about non-native species of plants and animals, we don’t usually mean horses or sheep, or wheat or barley or rice or potatoes – none of which are native to many of their current habitats around the world.

No, we mean animals like the albino California kingsnakes (Lampropeltis getula californiae) on the Spanish island of Gran Canaria, the progeny of escaped pets which are now decimating the native birds and lizard populations.

Or the voracious demon shrimp (Dikerogammarus haemobaphes), a Black Sea native that has been discovered in UK waterways, and whose impact on native species is as yet unknown.

As of April 2014, the European Parliament has approved new legislation aimed at controlling and eradicating non-native species that are considered damaging enough to be considered ‘invasive’ and dangerous to the survival of native species.

Albino California Kingsnake

Originally planned to be capped to fifty species, the blacklist will be now be unlimited, because there are simply too many species having a negative impact on native European biodiversity.

But what about the common rhododendron (Rhododendron ponticum)? While it’s not native to the United Kingdom, it has been widely used in hybrids, and is a well-liked botanical addition to gardens. And like many non-native garden favorites, it can be wildly successful at escaping and carpeting indigenous habitats.

If it makes the black list, will all varieties be banned? And how would that affect gardener’s preferences and choices – or the nurseries that breed rhododendron hybrids? Pet or plant, we always want what we want, when we want it.

Non-native species might be beloved as a domesticated varieties, but only as long as they obey our arbitrary rules of life, reproduction and geographical spread. Which they don’t, and almost never do.

Rhododendron ponticum, native to southern Spain, covers a hillside in Snowdonia, UK
Photo: M Williamson