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Why do Plant Names Keep Changing?

By 9 August, 2020September 9th, 2020No Comments

Have you ever had that moment when you notice an old favourite plant in a catalogue or nursery but the name next to it is not one you recognise? Don’t worry, you are not alone. Gardeners around the planet have spent the last 20 years or so embracing new names for once familiar plants. Remember Dicentra? It’s commonly known as Love Lies Bleeding but its botanic name was changed a few years back – welcome Lamprocapnos. It is of course the same plant but with a shiny new name, a bit like Reg Dwight becoming Elton John! I talk to gardeners all over the UK and particularly at my talks one of the most common questions is ‘why on earth do plant names keep changing. Are the botanists having a laugh?’ The answer is both simple and complex. The simple version is: plants are now named according to their DNA and familial links to other species. The more complex answer (its interesting, honest!) goes like this:

Historically plants were grouped together in families according to their flora structures. For example, the plant family Rosaceae has a broad range of plants included in it from roses to apples and strawberries to mountain ash. These plants all appear to be quite different in their form, structure, growing habit and leaves but they all have one thing in common. Every plant in the Rosaceae family has petals and stamens in sets of five.

This system certainly had a logic and has been the foundation of plant taxonomy and nomenclature for a few hundred years. Historically, when a new plant was discovered botanists would simply observe its flora structure and say ‘Ahh… it has this many petals and this floral form, therefore it is part of the Scrophulariaceae family’. But something changed a few years back. We made huge advances in science and were suddenly able to extract and decode DNA. First the fruit fly, then humans (turned out there was not much difference!) and finally scientists set to on identifying the DNA sequences of plants. Now, as you can imagine, this is no small undertaking. There are currently just short of 400,000 species on the planet so leading botanists around the world from organisations such the Royal Botanic Gardens Kew got together to divvy up the work and called themselves The Angiosperm Phylum Group. That may sound like a seventies prog’ rock group or some sinister asset management firm but it’s the name they settled on. Another key decision was made that the initial focus would be on monocotyledonous plants – in other words the bulbs, grass, palms, gingers, bananas. Still with me? Or, does the washing up suddenly look very appealing? Well hang in there, the revelation is but a few sentences away!

Scientists spent over a decade working on the monocotyledons and discovered that historical assumptions about which family or genus a plant belonged to were by and large correct but there were some anomalies. For example, there is a truly beautiful plant with grey-green bladed leaves and petite six petalled flowers with a peachy base spotted with orange and held aloft on fine wiry stems. It was called Belamcanda chinensis – a lovely sounding name. Unfortunately, once this plant had undergone DNA analysis it turned out that it was not a genus in its own right (Belamcanda) but was in fact an Iris. So, it’s been renamed. The once exotic sounding Belamcanda chinensis is now simply Iris domestica.

Once the Angiosperm Phylum Group (APG) had completed the palms, bulbs and grasses they set to on the broadleaf plants. And that is where we are today. The APG are working their way through tens of thousands of plants checking their DNA and whether they have the correct name. Again, many historic assumptions were correct, but some plant names have changed and I’m afraid to say there is more to come. But one day the plant name hylotelephium might just trip of the tongue as easily as its historic name – sedum… though replacing 2 syllables with 7 does not exactly help!