Tooth fungi and slime moulds

On Saturday 24th September I went to a public talk given by Paul Stamets, a mycologist from Washington State in the USA, who was visiting Findhorn for a couple of days. I had seen him give a lecture at Findhorn last year, and he’s a very inspiring speaker, speaking from the perspective of over two decades of studying and working with fungi, which he is convinced can be used to help address many of the environmental and health-related problems in our society today.

Paul is a wonderful character and gives his talks whilst wearing a hat made from a fungus – the felt-like material called amadou that is extracted from the tinder fungus (Fomes fomentarius). He lives and expresses his passion for all things fungal, and when I went to Glen Affric the next day I therefore had fungi on my mind, especially as this year has been such a good one for them.

After a quick stop at Dog Falls, where there was a hazel tree displaying beautiful autumn colours on its leaves, I went further into the glen to a spot where I knew that one of the rare species of pinewood specialist tooth fungi occurs. I had been told about that site many years ago by a friend who is a keen mycologist, but it was only in 2003 that I had first seen it myself, after having searched for it unsuccessfully the previous two years.

This species is the scaly tooth fungus (Sarcodon squamosus), and, along with the other tooth fungi that are associated with the native pinewoods, it is listed on the UK’s Biodiversity Action Plan as a priority for conservation. It had been a few years since I had seen this species at the site (mainly because I hadn’t been there at the right time of year), but in this remarkable year for fungi, there were quite a few fruiting, and much larger specimens than I had seen before – a couple of them were about 10 inches (25 cm.) in diameter across their caps!

Moving on again, I stopped to look at a fallen birch log, as there are often saprotrophic fungi growing out of dead wood like that. There were no mushrooms immediately visible, but I could see that a large section of the bark was loose, so I lifted it up and discovered a miniature wonderland of slime moulds fruiting underneath. I’ve had a growing interest in slime moulds in recent years and the more I learn about them, the more curious and fascinated I become.

Originally classified as fungi, slime moulds are now considered to be in a separate Kingdom of Life in the scientific system of classification, in the same way that, for example, plants, animals and fungi are considered to be separate Kingdoms. They also exhibit a number of remarkable characteristics, including a multi-phase lifecycle, in which they range from being individual cells to fusing together to form a multi-cellular plasmodium, and the ability to move or migrate over the substrate they occur on.

Interestingly enough, the movement of slime moulds is determined by the proteins actin and myosin, which also control the movement of muscles in vertebrates, including humans. Slime moulds have been shown to exhibit intelligence, with laboratory experiments demonstrating they retain a memory of recent events, and they’ve even shown that they can learn how to correctly navigate through a maze!

Just as it’s a great year for fungi, because of the wet summer we’ve had, so too did it seem to be an excellent time for slime moulds, as I found a couple of others during the course of the day. Stepping out of my car at one site in the glen, I spotted a black slime mould on the grass verge just a few inches away, and later on I found a white one on the forest floor – I’m still waiting to see if I can get those two species identified.

Postscript:  a week later, the next time I was out in Glen Affric, I returned to the same birch log, to see what, if anything, was still visible of the slime mould there. Lifting up the same loose piece of bark, there were still a few of the dark brown, older sporocarps visible, but most of them had released their spores already and were fading in colour to a dull beige and were also losing their shape.

However, elsewhere on the underside of the same piece of bark there was another slime mould species fruiting, with its sporocarps looking like insect eggs – a collection of white ovoid shapes, clustered together on the dead wood. I hadn’t seen this before, but I’ve subsquently had it identified as being Trichia varia. Slime moulds can generally be identified by their sporocarps, whereas it’s very difficult to identify them during their plasmodium phase.

On the outside of the log, though, was a much more obvious and readily-identifiable slime mould – Lycogala terrestre, sometimes known as wolf’s milk. A bright pinkish-orange in colour, darkening to brownish-grey, these fruiting bodies are relatively common on the outside of dead wood, and this is one of the most commonly-seen slime moulds in the Caledonian Forest.