Bean there, done that – 50 years at Kew

What secrets does our expert legume taxonomist have to share having spent half a century working in Kew's Herbarium?

Kew Scientist Gwil Lewis takes photos while laying on the ground

Standing amidst towering shelves of pressed plant specimens in Kew’s Herbarium, legume specialist Dr Gwilym (“Gwil”) Lewis has every reason to smile.

This year marks his incredible 50th anniversary of working at our Herbarium – and across those five decades, he and the legume team have painstakingly accessioned and curated more than 200,000 bean-related specimens of the around 700,000 we have at Kew.

We sat down with Gwil to learn how a chance knock on Kew’s door began a lifelong adventure in the world of pea and bean taxonomy.

Dr Gwil Lewis holding specimen Hymenolobium heringerianum that has pink flowers — Gwil holds a specimen from the Leguminosae family while in Brazil in 2023 *Hymenolobium heringerianum* © Domingos Cardoso

A fortuitous start

Gwil arrived at Kew in October 1974, not as a trained taxonomist but as a keen gardener, with a degree in botany and fresh from a long trip around Europe. ‘I knocked on the door of Kew Admin and asked if there was a job,’ he recalls.

‘A week later I was in the South Arboretum, pruning shrubs and tending the landscape. It was the famous Kew horticulturalist George E Brown who realised I wasn’t a proper gardener, but instead more of a scientist.’

George first suggested Gwil move indoors to assist with Herbarium curation, and after a short stint working on Rubiaceae (the coffee family), he jumped at an opening in the legume team. ‘I’d always been fascinated by legumes, from peas and beans to towering tropical trees and with huge economic and ecological importance.'

'The famous New York botanist Rupert Barneby once said: “You don’t choose legumes, they choose you.” Looking back, I think that was spot on!'

Dr Gwil Lewis in Baja California, Mexico — Gwil alongside Mexican botanist José Luis Contreras while on a field trip in Baja California, Mexico in the 1980s © Colin Hughes

Big changes over 50 years

When Gwil first started, Kew looked very different: ‘Back then, staff would gather for leisurely pub lunches, and you could smoke a pipe in the staff room. There were no computers, no mobile phones, and everything was typed in a “Typing Pool” by a team of dedicated ladies.'

These days, Kew has grown to include cutting-edge molecular labs, digitisation suites, and global collaborations on everything from plant taxonomy and climate adaptation to crop genetics.

‘In many ways, it’s even more exciting now,’ Gwil says. ‘We have powerful new tools like molecular systematics and bioinformatics. You can’t just announce a new species because “I say so.” You’ve got to present evidence that others can analyse and verify. It’s a new era of scientific rigour, but that core love of plants is the same as when I started.’

Dr Gwil Lewis in the field — Gwil stands next to shrubs of *Caesalpinia pulcherrima* while in El Salvador © Colin Hughes

Meeting Bente

Kew has also brought Gwil personal happiness too. In 1993 he met his future wife, Danish-British legume taxonomist Dr Bente B. Klitgård. ‘We bonded over our shared fascination with legumes and taxonomy. Bente is a world authority on rosewoods in the two genera Dalbergia and Pterocarpus, and we soon married in Denmark in 1995. We have a son, Kris, who’s now 29.

'Bente and I have done much fieldwork together, including in Bolivia, teaching students about taxonomy and conservation. It’s wonderful to share a passion for legumes with someone who’s just as committed to saving these species.’

Couple Gwil and Bente stand together in front of a scenery that shows a green-topped mountain in the background — Gwil has been on many field trips with his wife Bente © Gwilym Lewis

Secrets of the bean family

Legumes are the third-largest flowering plant family, ranging from tiny herbs to massive tropical trees and big woody lianas. As Gwil explains: ‘Legumes are vital for soil fertility through nitrogen fixation, and there are dozens of “orphan” crops we barely know about.'

“These under-utilised species might hold genetic traits that could help our major crops cope with climate change.”

'One example is the wild relatives of the peanut (Arachis). We only cultivate one species widely (Arachis hypogaea), but more than 70 wild species are out there. They might carry natural disease resistance or drought tolerance that we could breed into the major crop species.’

The orange flower of the plant that produces the peanut — We only cultivate one species that produces the peanut we're familiar with: *Arachis hypogaea* © Dinesh Valke from Thane, India, CC BY-SA 2.0

Describing the unknown

In his career so far, Gwil has named or co-named 11 new genera, 70 new species and 18 new subspecies or varieties of legumes. A handful of these have become stars in conservation efforts. One is a colossal tree from the Atlantic forests of Brazil, Dinizia jueirana-facao, whose trunk alone can weigh around 60 tonnes.

‘In 2017, we realised only 25 individuals were known to exist. Describing it for science gave it an identity, which is crucial for protecting it. You can’t conserve something if you don’t know it’s there.’

One of Gwil’s personal favourites include Ceratonia oreothauma (the species name meaning of the beautiful mountain top), found in Oman, which turned out to be only the second known species of the carob genus. ‘You feel this wave of excitement when you spot something unfamiliar. It’s like discovering a missing puzzle piece in nature. The sense of privilege and responsibility is huge.’

The seedling of the plant Ceratonia oreothauma — One of Gwil's favourite legumes is *Ceratonia oreothauma* © RBG Kew

Ceratonia oreothauma as a dried herbarium specimen

A curator’s pride

Over the years, Gwil has helped accession around 220,000–250,000 legume specimens for Kew’s Herbarium. ‘Those specimens are my “babies”,’ he laughs. ‘Someone goes out into the wild, collects and dries the plant, sends it to us, and we mount it on a sheet with all the key information.

Now, with digitisation, the entire world can see those specimens online. I encourage visitors to treat each specimen like it’s their child or their mother – they’re that precious.’

The future of legumes

With environmental change accelerating, Gwil believes legumes will only become more important. ‘As global temperatures rise, food production will face enormous challenges. Many legumes can grow in poorer soils, help fix atmospheric nitrogen, and are crucial sources of protein for billions of people.’

“We need to investigate lesser-known species that might become tomorrow’s staple crops.”

He also insists taxonomy is at the heart of protecting these plants: ‘If we don’t know a species’ name or distribution, we can’t talk about its conservation status.

Taxonomy is all other branches of the natural sciences. And, while artificial intelligence can help speed up identification, no machine can wander the Amazon, spot a new plant, and decide on the spot it’s something brand-new! Humans are still essential.’

Passing the torch

Looking back on his 50-year journey, Gwil says he hopes to leave two major legacies: ‘One is a world-class, accurately named and carefully curated legume collection, representing all 800 genera and a considerable portion of the 22,500 legume species.

The other is training students and collaborating with colleagues worldwide. Many of my former students now occupy top botanical positions. That’s incredibly satisfying. I know the next generation will take the field further than we ever imagined.’

Gwil holding up a plant — Gwilym has been on many fieldtrips over his 50-year career. Here he is holding up a species of the genus *Moldenhawera* © Toby Pennington

Asked if he’d recommend a career in taxonomy, Gwil beams: ‘Absolutely – if you’re passionate about plants, it’s the best job in the world. It’s true that you won’t get rich, but you’ll have decades of adventure, discovery and camaraderie. Travel, fieldwork, teaching, collaboration – every day is different. You just have to be ready for a lifelong learning curve!’

After half a century, Gwil shows no signs of slowing down. ‘There’s still so much to name, explore and protect,’ he says. ‘The beans might have chosen me, but I’m sticking with them for as long as I can.’