Groundsel (Senecio vulgaris)

Dear Readers, Groundsel (its name literally means ‘ground swallower) is one of the most widespread of ‘weeds’ – it pops up on the streets of East Finchley, the canals of East London, the Highlands of Scotland and more or less everywhere else in the UK and Ireland. You would think that we’d know everything to know about this vigorous little annual, but when I was reading my British Wildlife magazine today, I came across an article by Peter Marren, which made me consider what we know of even our commonest plants.

I’m currently getting stuck into the latest iteration of my Open University science degree, and for the first few weeks we have been much exercised by the whole idea of speciation, the process by which new species are made (once we can agree on what a species is, which is not as straightforward as you might imagine). Speciation in plants is even less straightforward – some of them can pollinate themselves, and this leads to high numbers of very local species – there are around 200 separate dandelions so far identified, and up to 400 species of bramble in the UK alone. But sometimes plants will create new species by hybridising with a closely-related species, and this has happened with groundsel.

Marren has identified two new species, both the results of crosses between Groundsel and Oxford Ragwort.

Oxford Ragwort (Senecio squalidus)

One species, the Welsh Groundsel (Senecio cambrensis), started life as an infertile hybrid, first identified in 1945 in Flintshire in Wales, and was known as Senecio x baxteri. At some point, a mutation occurred in this plant which meant that it was fertile, and could reproduce. Alas, Marren points out that it is not doing well – it seems to be particularly vulnerable to fungal disease. Like both of its parents, Welsh Groundsel is a plant of disturbed ground, cracks in pavements and brownfield sites, but these are precisely the areas that are often sprayed.

Welsh Groundsel (Senecio cambrensis) photographed near Chirk in North East Wales (Photo by By Alex Lockton – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=115207330)

The second species, also a cross between Oxford Ragwort and Groundsel, is the York Groundsel (Senecio eboracensis). First discovered in York in 1979, it was last seen in the wild in 1991, another victim of weed-spraying. Fortunately, the plant had already been recognised as a new species and seed was collected – York Groundsel was reintroduced to York last year. There is a very interesting article about the discovery and subsequent cultivation of the plant here.

York Groundsel (Senecio eboracensis) – Photo by Andy Shaw of the Rare British Plants nursery, via https://botsocscot.wordpress.com/2024/03/17/plant-of-the-week-18th-march-2024-senecio-eboracensis-york-radiate-groundsel/

So, the discovery of these two new species, hiding in plain view, begs a number of questions. Firstly, how easy is it to lose a whole species because there aren’t enough botanists (or entomologists/mycologists etc) to spot it in the first place. Secondly, how interesting that two different species have arisen from a native plant (Groundsel) and a non-native (Oxford Ragwort, originally from Sicily) when they were brought into close contact. We have so many plants brought from other parts of the world in the UK that I wonder how often this hybridisation occurs (and goes on to mutate further to produce a fertile new species) without being noticed. Officially, only six new species of plant (including these two Groundsels) have been discovered in either the UK or North America in the past century, but I wonder how many we’ve missed. And finally, how sad it is that new species arise and disappear so quickly. It’s one thing for a plant not to be well-adapted enough to survive under normal circumstances, it’s another for it to be blasted out of existence by over-enthusiastic weed-spraying.

All this has given me a real taste for the book from which Peter Marren’s article was taken – ‘Rare Plants‘, due to be published very soon. I tend to think of wild plants as being Bee Orchids or some Shetland speciality hiding away in a cleft of rock, but I’d never thought of our ‘weeds’ as being rare. I wonder if there’s an East Finchley Groundsel lurking somewhere? I shall have to get out the hand lens.

For more on ‘ordinary’ Groundsel, have a look here.

‘Ordinary’ Groundsel (Senecio vulgaris)