Fascinating fungi at Inverewe

Another small species of gill fungus that is occurring in large groups this year, under the pines and in bracken along the Pinewood Trail, is the inedible orange funnel-shaped false chanterelle (Hygrophoropsis aurantiacus) which resembles the true chanterelle or girolle (Cantharellus cibarius). Unlike its false counterpart, the true chanterelle is prized for its edibility, is yellow in colour with a pleasant smell of apricots, and occurs under broadleaved trees – especially oak and beech – rather than conifers. There are colonies of true chanterelles near the Cuddy Rock.

Also common along the trail under the pines are the uneven, pinky-orange caps of the terracotta hedgehog (Hydnum rufescens), often found growing in fairy rings. It looks like a gill fungus, but turning it over reveals the underside is covered with short and very fragile minute spines, hence the name. Like the chanterelle this is a very good edible species.

Yet another type of fruit body construction is the bolete, or tube, mushroom. Rather than gills, these have a layer of tubes under the cap. The largest of these is the famously edible cep or penny bun mushroom (Boletus edulis), which indeed has a rounded bun-shaped brown cap supported by a white chunky stem covered in a network of raised lines. Near to the Cuddy Rock one can find extraordinarily large examples under the beech trees, with some perhaps weighing several kilos. As they age, they are often taken over by a parasitic fungus called Sepedonium, obvious as bright yellow patches on the rotting fruit body.

There are more tube mushrooms to be discovered. Under the birches round the car park are the similar but more slender fruit bodies of the brown birch bolete (Leccinum scabrum), easily distinguished by a covering of black granules over the surface of the white stem. Very common under the pines is the slippery jack (Suillus luteus), well-named for its very slimy orange-brown cap, which has a shorter stem with a ring on it. Inverewe Garden also used to contain the yellow-capped larch bolete (Suillus grevillei), which will disappear along with the larch as the felling to control larch die-back continues.

This leads to the question as to why, in this account, fungi are mentioned as being found under a particular tree species. The reason is that the two – fungi and tree – are part of a mutually beneficial partnership, called a mycorrhiza (which literally means fungus-root). The top few centimetres of soil in woodland are often packed with a network of much-branched mycorrhizal roots. Under the microscope, these can be seen to be coated with the fungus, which extends out into the soil as a network of minute tubes (called hyphae) and more visible white cords (called the mycelium). Years of research have shown that the partnership works by the fungus system in the soil picking up important plant nutrients and passing them back to the tree via the mat of roots. In return, the fungus receives a flow of sugars in the reverse direction from the tree.

Many species of the mycorrhizal fungi specialise and this is simple to see when their fruit bodies only occur under one tree species, such as the larch bolete, or under a couple of species, like the fly agaric with birch and pine. Some other fungi have a much wider range of tree species as partners. For example, the deceiver (Laccaria laccata) can be found as small pinkish-brown fruit bodies under many host trees. In recent years, it has been realised that the relationship is much more complex than we thought, and has given rise to the concept of the ‘Wood Wide Web’, in which the fungi in the soil provide a connection between trees – for example with mother trees supporting seedlings via interconnecting fungi. Some have even proposed a type of consciousness for groups of trees, with the fungi acting as ‘neurones’ in a collective brain made of plant and fungus, which can pass messages about environmental changes between tree species!

Not all species of fungi in Inverewe are partners in this mycorrhizal system. Many are decomposers, rotting and recycling the plant debris: an equally important role in the food web. In fact, the false chanterelle (mentioned earlier) is one such decomposer, rotting the pine litter; in contrast, the true chanterelle is a mycorrhizal partner of oak and other broadleaved trees.

Some decomposers produce very tiny fruit bodies, only visible with a hand lens, on the surfaces of the rotting leaves and twigs, and even in compost heaps. There are many hundreds of these species, and only a few have been recorded at Inverewe simply because of lack of study. Others produce larger, easier to spot fruit bodies growing out of the forest litter: on the Inverewe lawns, in the flower and vegetable beds, and of course on dead wood throughout the gardens. These include the recognisable ‘mushroom’ shapes of gill fungi but also quite different structures: puffballs, stinkhorns, jelly fungi, shelf fungi, cup fungi, flask fungi and more. An account of these fungi, many of which we have also recorded on the Friends of Inverewe Forays, will have to be left for a future date!

| This article is not intended as a guide for foraging fungi, and should not be used as such. You should never pick or eat wild fungi unless you know exactly what you’re doing. |

Many thanks to Jim Henderson for kind permission to use his photographs.