16 October 2015

Introducing Kew's Fungarium and its treasures

Lee Davies, Fungarium Collections Assistant, introduces Kew’s Fungarium, which represents the most comprehensive collection of fungi in the world and is one of only several collections of fungi with a dedicated research team.

Researcher looking at fungal specimen

The Fungarium in numbers 

Kew’s Fungarium collection is arguably the best of its kind in the world; it has its own dedicated research team and an impressive number of well-curated samples and species, with many more being added each year.  

  • 1,250,000 – the minimum estimate of the number of fungal specimens we hold 

  • 60,000 – we have at least this many species represented in our collections, around 60% of the world’s currently known fungi 

  • 4,500 – the approximate number of new specimens received and integrated into our collections each year 

On a weekly basis, the diversity of species increases as we receive species new to our collections from researchers and institutions from all over the globe. Key to the success of Kew’s Fungarium are the working relationships with other institutions around the world with whom we exchange specimens to enrich our respective collections. 

In 2015, a brand new species of fungus, Geastrum brittanicum, was discovered in Norfolk. It had been collected 18 years ago, but it was only in 2015 that it was revealed to be a new species to science, with the aid of DNA sequencing. This highlights another reason Kew’s Fungarium is important: fungi are notoriously difficult to identify properly and it is only with the advent of quick and low cost DNA sequencing that we can really mine into familiar fungal species and discover that they are in fact several different yet similar species. If we were in a position to sequence all of our collections, we would undoubtedly uncover hundreds if not thousands of new species already in our collection. 

Historical and economically important specimens 

Amongst the 1.25 million specimens, we have some important historical specimens. For instance, we have specimens collected by Charles Darwin in South America whilst on the Beagle; Darwin preserved them in port until he returned to Britain. Alongside those, we also have subcultures of Alexander Flemings’s Penicillium: perhaps one of the most important fungal science discoveries in human history. 

Of course it doesn’t end there! What kind of fungarium would we be if we didn’t have other fungus-related items? Tucked away in a corner is a small collection of economic mycology specimens: fungi and fungal products that we make use of: an empty jar of marmite, dried porcini mushrooms from a supermarket and the brightest coloured specimens in the collection, a selection of wool samples that have been coloured using fungally-derived dyes. 

Contrary to what you might think, we also have tens of thousands of plant specimens in our fungarium. However, unlike the Herbarium collection, these are only here because they play host to pathogenic or parasitic fungi. We have an extensive collections of rusts and smuts (agricultural plant pathogens), which make up an important historical record of plant diseases and their diversity over time. The potential importance of these is made clear when you consider that we also have a specimen of potato blight from 19th century Ireland – which isn’t a fungus it turns out; it is in its own taxonomic kingdom with the slime moulds and is more closely related to plants than to fungi. Recent DNA studies compared those historical specimens to modern potato blight and found that they aren’t in fact the same strains at all. This has implications for how we treat pathogenic fungi when they affect crop plants. Our historical collections could be used to compare with modern outbreaks and offer up clues to treatments based on how those pathogens have or have not changed over time.

'Zombie' fungi 

Another group of pathogenic fungi we have in our collection, yet far more grotesque, are the Cordyceps fungi. These are the so-called 'zombie' fungi - their spores will infect insects and arachnids and slowly infest its body. After a while, when the fungus has become totally pervasive inside the unfortunate insect, it starts to take over it's biochemistry and alter it’s behaviour; the insect is driven to climb a plant and hang on. From there, the insect dies and the fungus sends its fruiting body bursting out of the corpse, sending out thousands of spores to infect more victims. As gruesome as this sounds, it can also be spectacularly beautiful to see the final fruiting fungus. This group of fungi are also of great importance to human welfare, as some of their mycochemicals have medicinal uses. Most of the immuno-suppressant drugs taken by transplant patients are derived from a chemical called cyclosporin that comes from a Cordyceps fungus. Another chemical, cordycepin, is currently being investigated for potential uses in treating cancers by restricting their spread throughout the patient's body. 

The Fungarium collection is one of the busiest at Kew (we receive more requests to borrow specimens from researchers all over the world than any other department), and relative to its size it receives more visitors than any other Kew collection. This will continue to be the case, as we are only really beginning to scratch the surface of the world’s fungal diversity, and the massive impact and influence they have over ecosystems and environments; through all of this Kew's Fungarium will continue to play a vital role.