Autumn is my favourite season of the year in the Caledonian Forest, and although I spend a lot of time appreciating and photographing the bright colours of the leaves on the deciduous trees, fungi run them a close second in terms of garnering my interest. This is the time when the majority of fungi produce their fruiting bodies and I’ve long been intrigued and fascinated by the diversity and beauty of the various forms they take.
Whilst some people might think of fungi purely as ‘mushrooms’, or even worse, ‘toadstools’ (fungi have nothing to do with either warty amphibians or faecal matter, as that derogatory term mistakenly implies!), I consider them to be members of one of the most wondrous and interesting of all the kingdoms of life on Earth. I’m constantly discovering new aspects of their biology, their relationships with other species and the functional roles they fulfil in ecosystems. My recent blog about the Hen of the Woods fungus is just one example of my ongoing explorations into the world of fungi.
This blog will be somewhat different to most of my other ones, in that it is not site-specific (many of my blog articles are focussed on a specific location, such as Dundreggan or Glen Affric, and a single day I spent there). Not all fungi fruit in the autumn, of course, so I thought I’d begin with a special one from Dundreggan that fruits in May each year – the tongues of fire, or juniper rust fungus (Gymnosporangium clavariiforme) that appears on junipers (Juniperus communis), and is particularly spectacular on wet days.
I’ve been aware of this fungus since my first spring visits to Dundreggan in 2006, and I usually look for them each year. On dry days they are quite inconspicuous, becoming shrunken and shrivelled up when they are desiccated, so rainy days are the best for seeing them. Like many fungi, they seem to have years of plentiful fruiting, and others when there are not so many visible at all. 2016 was a good year, so there were lots of them visible on many of the older junipers in particular in the native woodland on the estate.
This fungus has a remarkable two stage life cycle in which it alternates between two completely different hosts. When it fruits in May on junipers, the spores that it releases infect hawthorn trees (Crataegus monogyna), where the fungus induces the growth of galls on the leaves and fruits during the summer. Those galls have little tufts on them that release the fungal spores, which then infect juniper again, and so the cycle repeats each year. Having seen the tongues of fire at Dundreggan in May, I subsequently found some of the galls on a hawthorn tree in Glen Strathfarrar in early July.
At Dundreggan, I had a particular interest in the tongues of fire fungi this year, as a survey we had done for aphids at Dundreggan in 2015 had found some colonies of the giant juniper aphid (Cinara smolandiae) that appeared to be feeding on areas of thickened stems on some of the junipers. This aphid had first been found on Dundreggan in 2012, and as of today our estate is still the only known location for this rare species in the UK. The thickened stems of the junipers were thought to be the areas where the tongues of fire fungi fruit in the spring, but the survey in 2015 was carried out in July, so no fungi were visible then. I had marked a couple of bushes that were hosting the aphids at the time, so that I could check them next spring. Sure enough, when I visited those bushes in May 2016, the swollen stems were covered in the tongues of fire fungi, and there, amongst them, were the aphids feeding, and being tended by wood ants (Formica lugubris). This was great to see, and confirmed similar observations of a relationship between the fungus and the aphids’ feeding that have been recorded in Sweden.
It’s unclear what the exact relationship is between the fungus and the aphids at this stage. It’s possible that by causing the stems to swell, the fungus makes the wood easier for the aphids to penetrate with their rostra (as their feeding appendages are known). Another suggestion is that the distorted growth of the swelling entails more sap flowing there, and this in turn provides a greater food source for the aphids. Another aspect to the mystery is that the fungus fruits on many, many different junipers, but we’ve only found the aphids feeding on four or five of them so far – why don’t they occur on the other junipers as well? Is that dependent on the presence of wood ants nearby, that help protect the aphids from predators and parasites, while harvesting the clear liquid known as honeydew that the aphids excrete as a waste product, in this mutually-beneficial symbiosis between the ants and the aphids? There’s a great opportunity for a research project to tease out the details of the linkage between the fungus and the aphids, and we hope to find someone to work on this in the near future.
Staying with the colour orange for the time being, I found a fungus at 500 metres on Dundreggan on 8th September that I hadn’t seen before – it turned out to be the hotlips fungus (Octospora humosa). This grows as a parasite on some hair mosses, including species of Polytrichum and Hercynian haircap moss (Oligotrichum hercynicum), which it was fruiting with here at Dundreggan.
Almost exactly a month later I was back at virtually the same spot at Dundreggan, in the northwest of the estate, and I came across another bright orange coloured fungus. This is one I recognised immediately, as it is quite distinctive – the orange peel fungus (Aleuria aurantia). The derivation of its common name is very obvious, as the fruiting bodies resemble pieces of orange peel that have been cast down on the ground.
Unlike the hotlips fungus, this species does not grow in association with mosses and in fact is usually seen on bare ground, where there is no vegetation at all. It commonly occurs on disturbed ground beside paths, where there is gravel. In this case it was fruiting on an area beside the vehicle access track on the western part of Dundreggan, which was upgraded a few years ago for the renewal of the Beauly-Denny powerlines. The bare earth there makes it a classic location for this fungus.
Nearby is a good area for dwarf birch (Betula nana), a key species in the montane scrub community. There’s an unusual, black tar spot fungus (Atopospora betulina) that fruits on its leaves, and I soon spotted some of that as well.
Just a couple of days before that, I had been in Glen Affric and had come across another fungus that was instantly recognisable – the cowberry redleaf fungus (Exobasidium vaccinii), which induces the production of rather spectacular-looking galls on the leaves of cowberry (Vaccinium vitis-idaea). The galls mostly take the form of red, swollen cup-like shapes on the leaves, making them very distinctive and unmistakable. On some cowberry plants the fungus also induces pinkish swellings on the stems.
This fungus doesn’t produce a mushroom-like fruiting body, but instead its hymenium, or spore-bearing layer of cells, manifests as a white, felt-like layer on the underside of the galls. However, in this case it hadn’t yet reached that stage of development.
Also in Glen Affric, but about a month earlier, on 18th September, I had come across some more bright, orange-coloured fungi. These were on the underside of the leaves of an alder tree (Alnus glutinosa), and were a rust fungus (Melampsoridium betulinum) that also occurs on birches (Betula spp.) and larch trees (Larix decidua). Similar rust fungi grow on the leaves of other trees such as aspen (Populus tremula) and willows (Salix spp.), but they all tend to be relatively inconspicuous, so are often overlooked. I’ve seen them before on various occasions, but haven’t paid them that much attention. Looking closely now though, I discovered that there were some tiny orange larvae in amongst the patches of rust fungus, which matched the colour of the fungi almost perfectly.
Searching the Internet later that day, I discovered that they were the larvae of a (non-biting) midge (Mycodiplosis sp.), and that they feed on the spores of the rust fungus. There are a number of different species in the genus Mycodiplosis that feed in this way, and they can only be identified to species level from the adult midges, so the exact identity of these ones will remain unknown. However, the coloration of these larvae is another excellent example of camouflage in nature, which enables the larvae to feed on the rust fungi with a reduced risk of being spotted and eaten by insectivorous predators such as birds.
My initial purpose in producing this blog was to focus on a visual portrait of various fungi, but I’ve got slightly sidetracked with details of some of the interesting species I’ve seen in recent months. My original intention still holds true however, so the remainder of the blog will consist mostly of photographs, with a limited amount of text, to let the architecture and beauty of the fungi speak for themselves.
Photographed at Dundreggan in September, the common bonnet fungus is a small, seemingly unremarkable species, but it has a beautiful structure to the gills on the underside of its cap.
This next fungus looks superficially similar when viewed from above, but has a beautiful purplish colour to it, especially on the gills.
On the same day in Strathfarrar I found a somewhat tattered specimen of one of the brightly-coloured waxcap fungi – the splendid waxcap fungus (Hygrocybe splendidissima). I love the intensity and vibrant richness of its colour …
I spent the next day in Glen Affric, when I had the memorable encounter with the cormorant (Phalacrocorax carbo) that I wrote about in a recent blog. I also saw some fungi in the forest that day …
The first of these was one of the Russulas – I recognised it as one of them because of the colour and shape of the cap. This species gets its common name from the fact that the stipe or stem turns yellow after it has been picked.
A few feet away I found another fungus – one of the bolete group, which are distinctive because they have pores on the underside of their caps, instead of gills.
This was a species called Leccinum cyaneobasileucum, which has been given the provisional common name of greyshank bolete – this (and many other proposed new common names for fungi) is due for confirmation in March 2017.
While I was photographing the pore surface, I noticed a small invertebrate crawling around on it, which I recognised as being a springtail. I was able to get this identified later as being a common species called Pogonognathellus flavescens.
Although many people may only be familiar with the gill fungi, there are in fact several different types of underside surfaces to fungi, of which the pores of the bolete group are one example. Another group are the tooth fungi, which have ‘teeth’ instead of gills or pores, and during my next visit to Glen Affric on 28th October I found a couple of good examples of those.
One of them was a rare species, the scaly tooth fungus (Sarcodon squamosus) that is a specialist of old native pinewoods, and, as such, is a subject of the Biodiversity Action Plan for pinewood tooth fungi, which was designed to help conserve the group. I’ve seen this particular species at the same spot in Glen Affric over a period of many years – the fungus exists as a mycelium in the soil that is there all year round, so it’s fairly predictable to find it at this site each autumn.
What I didn’t expect though was to find such an enormous specimen of the fungus! This one, although past its best in terms of the freshness of its condition, was at least double the size of any that I’ve seen there before. The common name for this species is derived from the fact that the upper surface of the cap has concentric rings of flaking scales on it – these can just be made out in the photos here.
It is the teeth though for which this species, and the others in the group, are particularly noted. When viewed in close up detail, they look just like a dense concentration of miniature stalactites, hanging down from the underside of the cap.
While I was photographing the tooth fungus, one of my colleagues found a group of other fungi about 20 metres away, and he called me over to have a look at them. They turned out to be a troop of newly-emerged shaggy ink cap fungi (Coprinus comatus) in perfect condition.
I mentioned above that I found two species of tooth fungi in Glen Affric, and the second one was the wood hedgehog (Hydnum repandum). Unlike the scaly tooth fungus, this is a widespread species, and is the tooth fungus most commonly seen by people.
The specimen I found was growing in amongst some moss and other vegetation, and the cap wasn’t clearly visible, so I didn’t take any photographs of it before turning it over to look at the teeth underneath. These are quite different to those on the scaly tooth fungus, being shorter and more peg-like in shape.
The final few photos in this blog come from a trip that I made to Glen Affric on the 18th of December. After visiting the site of a potential new forest regeneration project there I stopped at an old birch tree near the road that has been dead for two or three years now. It’s had quite a few brackets of the birch polypore fungus (Piptoporus betulinus) visible on it for some time, and I’d had a good look at it about 18 months ago. Now I was curious to see what condition the snag (as standing dead trees are called) was in, as dead wood is an important habitat for a lot of organisms.
As soon as I approached the birch I could see there were some fungi visible on a large fallen branch that was lying horizontally on the ground, and these included some interestingly shaped specimens of the jelly rot fungus (Phlebia tremellosa).
This is a saprotrophic species, growing on dead wood, and its spore surface spreads over the surface of the wood, becoming wrinkled in complex, beautiful shapes.
In amongst the patches of the jelly rot fungi, there were several fruiting bodies of a gill fungus, and these looked to me to be the olive oysterling fungus (Sarcomyxa serotina). However, I was puzzled by the fact that they appeared to be fruiting upside down, as the gill surfaces were facing upwards. When I asked Liz about this, she replied that the fungi had probably begun fruiting normally when the branch was still attached to the tree, and it may only be because it had fallen, turning over as it did so, that they now appeared to be upside down.
The fallen birch branch was proving to be a good source of fungal diversity, and on another part of it, in amongst some moss, I discovered what turned out to be the sporocarps, or fruiting bodies, of a slime mould (Lycogala terrestre). For many years slime moulds were considered to be part of the fungal Kingdom, but more recently they have been re-classified to the Kingdom, Protista, along with some other unusual organisms. ‘Kingdom’ is the second highest level in the hierarchy of the scientific system of biological classification, and other Kingdoms include plants, animals, fungi and bacteria.
After looking at this fallen branch for a while, I turned my attention to the broken branch that was hanging down from the birch snag. There, I found a close relative of the jelly rot fungus – the wrinkled crust fungus (Phlebia radiata).
I actually thought these were the same fungi as before, but when I sent specimens to Liz, she identified them as two different species. The distinguishing features are apparently that Phlebia radiata has larger spores, and grows in a more radial pattern, as indicated by its specific epithet, radiata.
My original intention with this blog was to make it fairly simple and short, concentrating mainly on photographs that show the patterns, shapes and beauty of various fungi! However, as I’ve been working on it, it has taken on a life of its own, and has become something of a marathon effort – one of the longest blogs I’ve produced. I hope that it still serves the purpose though of celebrating the remarkable diversity and spectacular forms of some of the fungi that occur in the Caledonian Forest.
My thanks to Liz Holden for her help in identifying some of the fungi featured in this blog, to Peter Shaw for identifying the springtail and to Gordon Rothero for identifying the haircap moss with the hotlips fungi.