BFBI – Serratula tinctoria

Dr Richard Jefferson is the author of our latest Biological Flora of the British Isles article. Below he tells us more about his paper on saw-wort which was published in volume 105, issue 5 of Journal of Ecology…

Saw-wort (Serratula tinctoria) is a herbaceous perennial of the daisy family (Asteraceae) that occurs across much of Europe in a variety of largely open semi-natural habitats such as grasslands, fens and heaths.

My interest in the ecology of saw-wort commenced early in my career as a national specialist in lowland semi-natural grasslands working for English Nature (a Natural England legacy organisation).

In the many visits I have made to English semi-natural grasslands over the last 20 years or so, it struck me that sites with saw-wort were invariably of very high nature conservation value, and it was rare to find the species in grasslands that become degraded or partially agriculturally improved. In fact, this was clearly one of several species which one might term ‘high value indicators’, similar indicators sometimes occurring with saw-wort included betony (Stachys officinalis), dyer’s greenweed (Genista tinctoria) and devil’s-bit scabious (Succisa pratensis), at least in neutral grasslands.

In 2013, I was visiting Salisbury Plain, Wiltshire, one of Europe’s largest expanses of calcareous grassland, with Professor Richard Pywell of the Centre for Ecology & Hydrology (CEH) and on encountering saw-wort, I explained that this was one of my favourite species, on which Richard retorted “it’s mine too”. Richard was subsequently very helpful in the assembly of the account.

As to why it is a favourite of mine, this is more difficult to answer but I think it is probably a combination of its occurrence in special places and habitats, many of which are aesthetically pleasing (species-rich meadows, flower-rich chalk downland and calcareous fen-meadows) plus its overall attractiveness as a plant.

This made me start thinking that, in view of this, it would be an ideal plant to write a Biological Flora account for. Having already written a Biological Flora account for the woodland perennial herb, dog’s mercury (Mercurialis perennis) in 2008, (that’s another story!), I was fully aware of the existence of the long-running Biological Flora series and the value of the accounts for both researchers and conservation practitioners.

So the assembly of the account commenced in earnest in late 2013 and continued over the next few years, trying to fit work on the account around my grassland specialist role in Natural England. I was lucky enough to draw on the expertise and knowledge of several ecologists (in addition to Richard Pywell) – Dr Kevin Walker of the Botanical Society of Britain & Ireland who ultimately came on board as a second author, Dr Lucy Humes (CEH) who grew and drew the seedlings at the Grodome at CEH Wallingford and Dr Bryan Wheeler who supplied valuable ecohydrological data.

I learnt a great deal from researching the literature and writing the account but a couple of fascinating aspects emerged of which I was initially unaware. Although the epithet tinctoria should have been a clue, I hadn’t realised that saw-wort was used as a source of yellow dye in the 19th Century. It also produces phytoecdysteroids, secondary chemicals that are known to occur widely in plants and which mimic a hormone that regulates insect development. Their role and function is unknown but a compelling hypothesis, for which there is some evidence, is that they have a role in defence against generalist plant-feeding invertebrates.

And finally…early herbalists apparently “wonderfully commended saw-wort for treatment of wounds, ruptures, burstings, hernies and such like.” (The Herball, John Gerard, 1597)

Richard Jefferson (Natural England, UK)

Read the full paper here: Biological Flora of the British Isles: Serratula tinctoria

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