The Mushroom That Shouldn't Be Here

Sometimes finding a fungus is the beginning of a much bigger mystery.

In 2024 I found what looked like a Lentinellus growing on a conifer log in Denbighshire. There were a few things about it that didn't quite add up, though. Most obviously, it didn't have the characteristic aniseed smell I would expect from Lentinellus cochleatus, and it was growing on conifer rather than the more usual broadleaved wood.

Unfortunately, the fruiting bodies were already well past their best. It was late in the season, and the frost had done a pretty good job on many of the mushrooms around them. I took a good look at it, but there simply wasn't enough left in good enough condition for me to be confident about what I was seeing. I made a mental note of it as an interesting Lentinellus and carried on.

A week later, in Flintshire, I found what appeared to be the same thing again. Once more it was growing on conifer and once more there was no aniseed smell. This specimen was in even worse condition, so although finding the same unusual combination of characters in another county was interesting, I still didn't think there was enough evidence to take it any further.

At the time, I had no idea that I was going to be seeing a lot more of this fungus.

Finding an answer

In 2025 I found more fruiting bodies on that same log in Denbighshire. They were again past their best, but this time I was determined to work out what I was looking at.

I took a specimen home and started going through my books. I worked through the European species in the family and related groups, comparing descriptions and illustrations, but nothing seemed to fit properly. It had the appearance of a Lentinellus, but the combination of characters wasn't quite right.

Eventually I did what anyone who spends too much time looking at fungi eventually does: I turned to the internet.

Of course, the internet can be a dangerous place for fungal identification. There are plenty of photographs labelled with species names that are simply wrong, and it is very easy to convince yourself that something is a match because you desperately want it to be. But this time the search produced something that really caught my attention.

Neolentinus kauffmanii.

The photographs looked remarkably similar to what I had been finding. The descriptions fitted too. The more I investigated, the more I thought I might have found the answer.

There was just one rather enormous problem.

Neolentinus kauffmanii is a species associated predominantly with the Pacific Northwest of North America. This was a fungus I was finding in North Wales.

There were no UK records that I could find, and very few well-verified records from Europe. My specimen certainly looked like it, but looking like something on the internet is not enough, particularly when the proposed identification involves a species from the other side of the Atlantic.

So I decided to get it properly tested.

I dried the specimen and sent it to David Harries in Pembrokeshire, who extracted the DNA before sending it to Aberystwyth University for DNA barcoding.

Then came the result. 100% match: Neolentinus kauffmanii.

The strange mushroom I had been finding in North Wales really was Neolentinus kauffmanii.

And that left me with a much bigger question.

What on earth was it doing in North Wales?

A Pacific Northwest species in Wales

Finding an apparently North American species in North Wales is the sort of thing that makes you stop and look at your records again.

Was this a recent arrival? Had it been introduced somehow and subsequently established itself here? Was it associated with imported timber or forestry? Or had it actually been here for much longer and simply been overlooked?

At this point, we don't know.

One thing that makes the story particularly interesting is how difficult this species would have been to recognise historically. If you found an unusual Neolentinus or Lentinellus-type fungus in North Wales several decades ago, your identification would have depended almost entirely on the books and literature available to you.

There was no Google image search. There were no online fungal databases containing photographs from around the world. There was no iNaturalist, no Mushroom Observer and no easy way of comparing your Welsh specimen with photographs of an obscure fungus from the forests of the Pacific Northwest.

And Neolentinus kauffmanii isn't in the European identification books I have on my shelves.

So if somebody found one in North Wales in, say, 1960, what would they have called it?

Probably whatever it most closely resembled in the literature available to them.

That is where things get particularly intriguing, because there are historical records of Lentinellus from the area. I wouldn't suggest changing any of those records without examining the original specimens, and at the moment it is only a possibility, but I can't help wondering whether some of these old records could eventually turn out to have been Neolentinus kauffmanii.

It raises the possibility that this isn't necessarily a fungus that has recently arrived in Wales at all. Perhaps it has been here for decades, quietly growing on conifer timber and being recorded under another name.

Or perhaps it really is a recent arrival.

At the moment, there is no way of knowing.

And then I found it again

You might think that having solved the mystery with DNA would have been the end of the story. It wasn't.

Last week I was filming my next YouTube video near Rhyd Ddu in Eryri when I came across a mushroom growing from a rotting spruce stump. I walked over to have a look, and almost immediately I knew what I was looking at. Neolentinus kauffmanii.

After the previous specimens, the combination of its appearance, the substrate and the habitat was immediately familiar. I had found it again.

This time, however, it wasn't Denbighshire or Flintshire. It was Gwynedd.

So in the space of two years I have now found Neolentinus kauffmanii in three different counties of North Wales. Denbighshire. Flintshire. Gwynedd.

That makes the original question even more interesting. If this were just one isolated population, it would be tempting to regard it as a local curiosity. But finding it repeatedly, in different places and across several counties, suggests there may be considerably more of it out there than we currently realise.

And if I'm finding it, perhaps other people are too.

How long has it really been here?

This is probably the part of the story that interests me most. We tend to think of species distributions as fixed things: a species occurs here, it doesn't occur there, and at some point it crossed a line on a map. But with fungi, our maps are often maps of where somebody has looked, recognised the species and recorded it.

Those are not necessarily the same thing. A fungus can be sitting in a woodland for years without anybody noticing it. It can fruit for a few days, disappear again and perhaps not be seen for another year. If it resembles a more familiar species, it can be recorded under the wrong name. And if the species isn't known from Britain in the first place, there is an obvious tendency to look for a familiar explanation rather than assume you have discovered something completely unexpected.

DNA has changed that to some extent, but even DNA can only answer the question we put to it. In this case, it told us that my specimen was Neolentinus kauffmanii. It didn't tell us when the species arrived in Wales, how it got here or how widespread it is.

Those questions remain open. For now, I will be keeping a very close eye on suitable coniferous timber wherever I am working in North Wales. I'm particularly interested in whether other recorders begin finding it, and whether some of those old Lentinellus records might be worth revisiting.

There is also the possibility that it occurs elsewhere in Britain and simply hasn't been recognised yet. That is one of the things I love about fungi. Even after spending decades looking at them, you can still walk into a woodland and find something that completely changes what you thought you knew about the place.

In 2024 I thought I had found an odd Lentinellus that was past its best.

In 2025 I discovered that it was a species from the Pacific Northwest that apparently wasn't known from Britain.

And now, in 2026, I have found it again in a third North Wales county.

So I still don't really know how long Neolentinus kauffmanii has been living in Wales.

But I know one thing for certain. It is here now. And I suspect this may be the beginning of a much bigger story.

Dave.