A new discovery at Dundreggan

In the middle of December I was out at Dundreggan with a couple of my colleagues, including Doug Gilbert, our Operations Manager at the Estate, and Colin Blyth, a consultant whom we work with on our forest restoration projects there. The reason for our visit was to scout out the possible line of a new fence for our next tree planting scheme on the estate. However, the day turned very wintry, with blizzards and white-out conditions, so we had to abandon our mission, and Colin and I decided to walk back to the lodge, down through the woodland on the east side of the Allt Ruadh, or Red Burn.

As we came down into the trees from the open hillside higher up, we gained some shelter from the gusting wind and driving snow, although it was still very cold. Reaching a small gully near the top edge of the woodland, we paused for a few moments near an old downy birch tree (Betula pubescens) that had been able to grow to a larger size than its neighbours, because of the shelter provided by the gully. One large branch of the tree had died and was resting, partially fallen, at an angle of 45 degrees. The branch was mostly covered by snow, but in one place my eye was drawn by some bright orange shapes – the small brackets of a fungus.

I wasn’t able to make an identification of the fungus at the time, but a week later, when I was back at Dundreggan again and the snow had melted, I returned to the site with Doug to have another look at it. With better light and no snow I could examine the fungus more closely and I saw that it was the hairy curtain crust (Stereum hirsutum). This is a common and widespread species in the UK, which gains its common epiphet ‘hairy’ and its specific name ‘hirsutum’ from the hairy upper surface of the brackets when the fungus is young. Other characteristic features are the orange colour and the occurrence of multiple brackets together, which, along with their rippled edges, give rise to the ‘curtain’ part of the common name.

I’ve seen and photographed this species before, both at Dundreggan and elsewhere, and I should really have recognised these specimens when I first saw them the week before. I put my failure to do so down to being tired at the end of an arduous day in the cold and snowy conditions, and only having a brief moment or two to look at them then! The fruiting brackets of this fungus are tough and leathery, and can persist for a year or so. They fruit on the dead wood of broadleaved trees such as oak (Quercus spp.) or, as in this case, birch.

When I approached the tree this time though, in addition to this bright orange bracket fungus, I saw there was another different fungus fruiting close by on the same dead branch. This was much larger, pale brown in colour and consisted of a dense group of jelly-like lobes. I didn’t recognise it, but I assumed it must be one of the group of jelly fungi. I was also slightly surprised to see a fungus like this fruiting in the middle of December, as it seemed too delicate and fragile to survive in the snow and cold of winter.

I was quite fascinated by this fungus, and began taking a series of photographs of it, getting progressively closer to reveal the details of the lobes and their translucent appearance. The shape also intrigued me, with the lobes overlapping and forming aesthetically-pleasing combinations of undulating fungal folds. They provided another expression of the limitless creative artistry of Nature, and an ephemeral one at that, as I guessed that this fungus, consisting largely of water, would not persist for long at all.

Later that day, back at home, I did some research on the Internet to discover what species this fungus was and quickly found some photos that looked the same on several web pages. It was one of the gelatinous fungi in the genus Tremella, and the particular species looked like one called the leafy brain fungus (Tremella foliacea). When I read about the Tremella fungi, I discovered that they are parasites of other fungi – including the group known as corticioid fungi, which is the scientific name for crust fungi – and that the leafy brain fungus is a parasite on the hairy curtain crust fungus (Stereum hirsutum). This explained why the two species had been occurring so close together on the dead birch branch!

This was very interesting and exciting for me, and I sent samples of the two fungi off to Liz Holden, the mycologist who helps me with fungal identifications. She was able to confirm that I was correct with the names in both cases. Although I’d seen and photographed the hairy curtain crust before, I hadn’t been aware of the fact that it was parasitised by another fungus, so this was a new discovery for me, adding to my understanding and knowledge about the complex and fascinating relationships that fungi have with other organisms. It was also the first record of the leafy brain fungus for Dundreggan, so it was good to add this species to our list of the biodiversity (now over 3,000 species) that has been recorded on the estate.