BSBI Handbook #22: Broomrapes of Britain & Ireland: interview with Chris Thorogood (joint author)

There’s a new addition to the series of BSBI Handbooks. Broomrapes of Britain & Ireland is due to be published on 1st May and BSBI members will be able to benefit from an exclusive introductory offer of £12.50 (plus P&P) which will save them £5 compared the RRP of £17.50.

There are two authors behind this new book: Prof Chris Thorogood – Deputy Director and Head of Science at University of Oxford Botanic Garden & Arboretum, author, artist, media star… - and Dr Fred Rumsey, Senior Curator in Charge of Historical Collections, Algae, Fungi and Plants Division, Life Sciences Department at the Natural History Museum, London. Fred is already well-known to readers of this News blog, but Chris maybe isn’t, so I approached him first and asked him to tell us a bit more about himself and about Broomrapes of Britain & Ireland…

LM: Chris, before we start talking about the new Handbook, could you tell us a bit more about yourself please, how you got started as a botanist, some of the many strings to your bow and your particular area of botanical interest?

Chris in his element, hanging
out with water-lilies

CT: Sure Louise! Well I have been fascinated by plants for as long as I can remember. As a kid my bedroom windowsill was a bit of a jungle. And I was growing broomrapes at the age of 12 – I guess it was inevitable that I was to become a botanist really! Today, I am the Deputy Director and Head of Science at the University of Oxford Botanic Garden and Arboretum. The research I do here centres on processes that shape the evolution of parasitic plants and also carnivorous plants – those that can obtain food in ways other than photosynthesis.

 I also work on the floras that grow in Biodiversity Hotspots (priority areas for conservation) around the world, for example Japan and the Mediterranean, and in the Middle East. Working with scientists from other disciplines, such as physics, another aspect of my research examines how plants can inform design in technology. My work has taken me around the world where I have been lucky enough to see some beautiful plants in breath-taking places. My passion in life is painting. When I’ve seen something beautiful in nature (which luckily for me happens quite a lot), well I just have an irrepressible urge to capture it on canvas… And when I’m not scribbling or messing about with plants, you might find me tweeting, posting things on Instagram or chatting away on BBC Radio 4’s Gardeners’ Question Time.

Pages from the new Handbook...

LM: Blimey, you’re a busy man and a bit of a botanical superstar! So how did you become involved in working on this BSBI Handbook?

CT: Years ago, my PhD research examined broomrapes Orobanche. I used molecular tools to answer evolutionary questions. In other words, in the lab, I examined broomrapes’ DNA to find out how they were forming new species. The results were surprising and quite exciting: populations of common broomrape O. minor that looked the same, were behaving very differently. In short, our work showed that they were adapted to specific hosts (clovers for example); and because different hosts have different preferences (sea cliffs, fields, car parks etc.), populations of broomrape can become genetically isolated from one another. And this paves the way for new species to evolve – a process we call incipient speciation.

You can find out more about one of the forms we described last year here.

Orobanche minor - this one is
subspecies maritima
Image: C. Thorogood 

LM: Ooh that’s based on this paper that you and Fred submitted to British & Irish Botany, BSBI’s Open Access, in-house scientific journal! Any News & Views readers who missed out on the paper last year (we flagged it here) can read it now – it’s a corker and beautifully illustrated by Chris and Fred!

CT: The handbook includes observations we made during the course of that research, and the many years that my co-author Fred and I have spent in the field, peering at broomrapes

LM: That’s ok Chris, you’re among your people here – BSBI has thousands of members who spend their time in the field peering at plants! So, the new book is 152 pages long, covers 16 species and 7 infra-specific taxa in the family Orobanchaceae. When did you and Fred start working on the book?

CT: You could say that the idea for the handbook has been knocking about for years. But in fact we only started working on it in earnest last summer (July 2020). Fred and I got so carried away that we spent many long nights and weekends working on it (obsessively some might say), so we finished it in a much shorter time than expected.

LM: Well we’re very glad that you did! Can you give us an example please of one of the species you cover and what we can expect to find out from the new Handbook about its identification, distribution and current conservation status?

Orobanche picridis
Image: C. Thorogood

CT: Sure. Picris broomrape Orobanche picridis is an exceptionally rare species with only two thriving colonies in the UK (and absent entirely from Ireland). Well-developed specimens are pretty easy to identify; the trouble is, smaller ones look a lot like their cousin, the common broomrape (O. minor), which as its name suggests, is a lot more frequent. In the book we grasp the nettle on this parasitic plant puzzle, giving a lot more detail on how to tell apart this taxonomically troublesome pair than other guide books would have the inclination to do. I hope that the reader would be left in little doubt about what was in front of them!  

LM: Sounds like you and Fred visited a lot of locations across Britain and Ireland in the course of your research. Are there any that particularly stand out in your memory?

CT: Well Louise our broomrape safaris have taken us to some glamorous places, from supermarket carparks, to death-defying cliffs! When we weren’t ducking golf balls on Sandwich Bay golf course or taking the occasional abseil down a sea cliff, I guess I would have to say my favourite stomping ground for the plants is around Essex and Kent. Fred and I both grew up in this area, and in some respects, this region is the broomrape capital of Britain and Ireland. That said, beautiful broomrapes grow up and down the region, often in some very beautiful places indeed.

LM: Ooh so lots of opportunities to visit lovely places and peer at plants – that sounds like great fun! How about herbaria – did you two visit many herbaria to look at specimens? On which subject – how exactly do you press a broomrape? They are quite chunky! Do they have to be pickled rather than pressed?

Pages from the new Handbook...
these show the life-cycle of 
an Orobanche

CT: (Face-palm emoji) ahem broomrapes and herbaria…. well the thing is, they preserve terribly, Louise. This is a real headache for the broomrape connoisseur. They have no leaves to speak of, and their colours (lovely in life) turn a rather hideous shade of yellow or brown. In short, we’re left with a squashed asparagus. I exaggerate: in fact, there is a lot you can tell from a herbarium specimen if you look closely, for example the calyx shape, the amount of hairiness of the floral parts, and multifarious other bits and pieces. But is isn’t easy. Pressed specimens are best if they include notes on colours seen at flowering time, possible host plant species, and, best of all, a floral dissection or two.

LM: Yes, as we always say about herbarium specimens, the supporting info is as important as the specimen itself. And thanks for confirming my suspicions about the difficulties in preserving broomrape specimens – squashed asparagus indeed! But moving on, I imagine you also got a lot of feedback from BSBI County Recorders and many of our “ordinary members” who go out plant recording?

CT: BSBI County Recorders and enthusiasts up and down the country are incredibly helpful Louise. The maps in the handbook simply wouldn’t exist without them. And many provided their photos too. Our sincere thanks to you all.

Some of Chris's pen & ink drawings

LM: Yes, the BSBI community is amazing – whether recording, taking photos or trying to press plants for herbaria... You mentioned photos so let’s turn to the illustrations: they are always an important part of any BSBI Handbook and Chris, you are famous for your amazing plant illustrations. Could you tell us a bit about how you produce your drawings and your colour illustrations, how long it takes you and what materials you use?

CT: Thank you Louise. Fred and I both illustrate. I often use pen and ink which is quite a precise way to capture a plant, and is the perfect medium for depicting, for example, hairiness (an important diagnostic in broomrapes). I also use watercolours and (less conventionally) oil paints (which were used for the front cover). I find oils capture the soul of a plant in the way watercolours cannot always. If done in a leisurely way, a line drawing can be done in a day; a watercolour in a week; an oil painting in two.

Pages from the new Handbook...

LM: Are there photographs too?

CT: There are (quite a few in fact), but I am not really a photographer. Many people very kindly provided their photos for the book and it wouldn’t be the book it is without them.

LM: Yep, that amazing BSBI community again! I hear there are also BSBI distribution maps for the taxa, and that some of the maps compare the distribution of the various taxa with their primary hosts?

CT: Correct. We were fascinated by the idea of charting host and parasite in parallel to see if there were any insights as to why the broomrapes occur where they do. Interestingly, by way of example, thistle broomrape is exceptionally rare and confined to Yorkshire; yet its most common host – the creeping thistle Cirsium arvense is of course ubiquitous. There is a lot more than meets the eye to these very particular plants, clearly.

LM: Yes, they certainly are intriguing and that’s one reason why BSBI’s Publications committee thought people would be interested in a Handbook all about them. Finally: all BSBI Handbook authors benefit from an editor to help them through the process towards publication. Who was your editor?

Chris admiring an Orobanche

CT: David Pearman was our very patient editor, to whom Fred and I most certainly owe a debt of thanks.

LM: Wow, David is a legend (newcomers to BSBI can read a bit about him here), so well done you for bagging him as your Editor! Well the new Handbook really does look amazing, many thanks to you and Fred for all your hard work that has brought us this fabulous new addition to BSBI’s publications portfolio and thank you also for talking to us today. Before you go, may I issue an invitation to you please? We are not sure at this point if our 2021 Exhibition Meeting in November will be held as a live event at the Natural History Museum in London or as a zoom event – or perhaps some kind of hybrid! But in whatever way it takes place, would you be up for giving us a short talk about broomrapes, maybe a poster too and perhaps we can have some kind of promotion around the Handbook? Fred is always involved in our Exhibition Meetings but it would be great to have both Handbook authors on the day – so, how about it?

CT: I would be delighted to, Louise.

LM: Thanks Chris, it’s a deal! Now, readers will want to know how to get hold of a copy of the new Handbook.

If you are a BSBI member, there is a flyer tucked inside the April issue of BSBI News which is winging its way to you as we speak. It explains how BSBI members can benefit from our exclusive offer and save £5 compared to the RRP. You can either use the flyer to order your copy by post before the end of June or else click here to order your copy via the password-protected members-only area of the BSBI website (you'll need to have your password to hand – email me if you’ve forgotten it and don’t forget to include your membership number).

If you are not a BSBI member, you have two options: you will be able to buy the book from Summerfield Books and other natural history book-sellers in June. Or why not join BSBI today and start enjoying all the benefits of membership, including this special offer? Take a look at our Join Us page  which lists all the benefits of BSBI membership and there's a secure payment option, making it very quick and easy for you to become a BSBI member and start getting involved.