3 March 2025
5 min read
What’s it like working with Kew’s Herbarium collection?
From uncovering plant specimens to helping organise Africa’s ‘naming wall’, PhD student Ellen Heimpel shares what she learned during her placement at Kew.
Our Herbarium collection is one of the largest in the world, home to around seven million preserved plant specimens. Each specimen holds a wealth of information: where and when it was collected, who found it, and what species it belongs to.
These collections are used by scientists worldwide to help name and classify plants, track biodiversity loss, and even identify species new to science.
For the past three months, PhD student Ellen Heimpel has been working with our Africa curation team, getting hands-on experience with this vast botanical archive.
Ellen’s research focuses on the tropical forests of central Africa, particularly areas where a single tree species, Gilbertiodendron dewevrei, dominates the canopy. Her time at Kew has helped her understand the vital role herbaria play in conservation and plant science.
‘Herbarium specimens hold so much information. I wanted to understand how they’re identified, organised and used for research – and to get involved in the curation process myself,’ she says.
What’s in a name?
One of Ellen’s main tasks at Kew was working on the Africa ‘naming wall’ – an area where unidentified specimens are stored, waiting for expert attention. Each specimen is sorted by plant family and region, but many remain nameless, sometimes for decades.
‘I started with specimens from the Annonaceae family – the custard apple family – as it was a group I knew well from my PhD research. Identifying a plant involves using Floras – books or online resources that provide identification keys – and carefully examining a specimen under the microscope. Then, I’d compare it with correctly named specimens in the collection to confirm its identity.’
Some identifications were relatively quick. Others took hours.
“One specimen of Eriocaulon schimperi, collected in Malawi in 1970, had been sitting in the naming wall for over 50 years.”
‘There was no Flora for Malawi, so I used the book Flora Zambesiaca, which covers several southern African countries. I worked through the key, checking the description against the specimen. Finally, I found a match. After 54 years, this specimen had a name.’
With around 18,000 new specimens arriving at Kew every year – many without names – the naming wall is an ever-growing challenge.
A plant treasure trove
During her placement, Ellen helped catalogue and organise the naming wall’s contents, sorting specimens by country and family. Before she started, there were 870 specimens in the wall. By the end of her placement, she had identified over 150 – a very impressive feat – but hundreds more remain.
‘The most common country of origin was Madagascar, with 279 specimens, followed by Cameroon, Tanzania, Gabon and Malawi. The plant families with the most unnamed specimens were Sapindaceae, Asteraceae, Euphorbiaceae and Rubiaceae. Some of these are likely to be undescribed species, particularly from regions like Madagascar and Cameroon, which are still poorly studied botanically.’
This is a considerable problem because if we don’t know a species’ name, we can’t talk about its conservation status. Taxonomy is the foundation for everything else as was recently detailed by fellow taxonomist Dr Gwil Lewis who celebrates 50 years of working on Legumes at Kew this year.
Among the specimens she worked on, one was a specimen that was later found by Kew Scientist Martin Cheek to be new to science. ‘One specimen from the naming wall was recently described as Monanthotaxis bali, a Critically Endangered treelet from Cameroon. It had been sitting unidentified for years – a reminder of how valuable these collections are.’
The journey from field to cupboard
Beyond naming plants, Ellen got stuck into the daily work of a herbarium curator, helping process new specimens from Kew’s field expeditions.
‘Once a specimen arrives, it needs to be named, labelled and entered into the database. Then it’s prepared for mounting, ensuring key plant features are visible and preserving material for DNA analysis. Preparation is one of my favourite parts – it’s meticulous but creative, making sure the specimen is both scientifically useful and visually beautiful.’
Once mounted, specimens are digitised and stored in the herbarium cupboards. But with millions of specimens to manage, space at a premium and number of people accessing them limited, careful organisation is key. ‘A lot of my work involved laying away newly mounted specimens – making sure they’re stored in the right place, otherwise they could be lost forever!’
Reflections on three months at Kew
Ellen’s biggest takeaway? The behind-the-scenes work of herbarium curators is vital to keeping these collections accessible for research.
‘I hadn’t realised just how many stages a specimen goes through before it’s available for scientists to use – or how much skill is involved in every step. Keeping a collection this large organised is a huge challenge, especially as plant names change over time. The curators at Kew do an incredible job managing around seven million specimens.’
Her placement has also made her think about the global challenge of identifying herbarium specimens. ‘It’s easy to assume that all plant species have been named, but my time at Kew showed me that’s far from the case.
There are still thousands of unidentified specimens here, and likely millions across the world’s herbaria. Finding ways to speed up this process is crucial for plant science and conservation.’
So, would she recommend a placement at Kew? ‘Absolutely. If you’re a PhD student interested in plant taxonomy, ecology or conservation, Kew is an amazing place to learn. There’s still so much work to be done!’
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