Macrofungi of Haweswater’s Mirkside

Many of us are familiar with the wildlife the calls Haweswater home, mammals, birds and wildflowers are a particular focus of many of visitors, but there is an entire Kingdom – Fungi – often passed by.

We are delighted to share this fascinating new report by Cumbria Fungi Group, compiled by Paul Nichol, following the group’s extensive surveys and listing of fungi within Haweswater’s Mirkside Wood.

During 2020 the recording activities of the Cumbria Fungi Group were severely curtailed due to the Covid pandemic. However it became possible during the autumn for a small group to undertake a series of visits to RSPB Haweswater in order to record the Macrofungi of a particular woodland area following a request made by the reserve manager Lee Schofield some time earlier. Little previous recording of the mycota had been undertaken on any part of the reserve, and the small number of records that do occur have been compiled following visits to the reserve by individuals. In September 1995 The British Mycological Society visited the Low Forest and Hugh’s Laithes Pike areas and recorded forty species.

Mirkside Wood an area of deciduous woodland has developed on a steep NW facing valley side through which runs Naddle Beck a small spate river. The wood rises from the valley floor at 300m up to Harper Hills at 400m. The slope is quite steep with large areas of loose rocks and rock outcrops and there are numerous rivulets running down to Naddle Beck which after rain makes the floor of the woodland very wet particularly in the lower part. Soils tend to be thin due to the rocky nature but soils have developed in some areas where the slope is less. Naddle Forest NVC indicates that Mirkside has a crown canopy dominated by mature Quercus petraea (Sessile Oak) and Betula pubescens (Downy Birch) at the top of the slope giving way to Fraxinus excelsior (European Ash) and Alnus glutinosa (Alder)at lower levels.

The understory and shrub layer consists of extensive coppiced Corylus avellana (Hazel) with some Sorbus aucuparia (Rowan) with occasional Crataegus monogyna (Common Hawthorn). The vegetation of the field and ground layers consists of extensive bryophyte cover on the rocks with the angiosperms Lysimachia nemorum in the wetter areas, and Mercurialis perennis and Oxalis acetosella further up the slope, all three suggest that this is a seminatural ancient woodland and part of the “Atlantic rainforest”. In more open areas Pteridium aquilinum has invaded and densely covers the slope. Strewn across the floor of the woodland there is much dead wood in the form of fallen trunks and branches with some of the trunks being of a considerable size.

Recording was undertaken during monthly visits between July and November with members of the group respecting government guidelines concerning social distancing. If identification was possible in the field then a record was made along with the substrate on which the fungus was growing and its association with trees etc. Unidentified specimens or critical species were taken for later examination and confirmation.

Table 1 below shows the species recorded during the project and the times of their appearance. One hundred and thirteen fungi species were recorded and as would be expected only a small number had made an appearance during the summer in July increasing somewhat in August. As the fungus season got going in September the number of species recorded increased and this continued into October. A further visit in mid November may have added a small number of new species to the list but by then the weather had deteriorated and moving in the wood would prove very difficult, in fact on one of the visits Naddle Beck was in spate and it was very difficult and dangerous to exit the wood.

A record for the area was submitted in January by Chris Cant for Onygena equina The Horn Stalkball, made on 25.12.2020. Onygena occupies a very specialised niche being one of very few fungi that can feed on Keratin, the substance of which horns and hooves are made. This fungus along with four others are on the UK Red List*.

Fungi species on the UK Red List, found at Haweswater

Amanita betulae   Endangered             

Inocybe phaeodisca  Vulnerable

Onygena equina  Near Threatened 

Russula pelargonia Vulnerable

Russula pumila  Vulnerable     

Table 1. Species recorded during project, with times of appearance. Those in red are included on the UK Red List.

Table 2. Morphological groups.

Fungi attain their greatest diversity in woodlands probably because there are innumerable niches in these ecosystems that they can occupy to undertake their role as essential nutrient recyclers.                                                                     

Table 3 below shows the feeding relationships of the fungi in the woodland ecosystem. Those that are Ectomycorrhizal with the trees and shrubs, that is growing in physical contact underground with the roots of trees. This relationship is symbiotic and some fungal species are very specific as to their partner.  Lignicolous fungi feed in different ways on wood, they may be (as most are) saprotrophic feeding on dead wood or parasitic feeding on living wood. The third category are the Terrestrial fungi which are important decomposers of material on the floor of the woodland particularly leaves but also flowers, fruits etc.  

Within a woodland the diversity and number of fungi that occur depends on many factors but probably the most important are the niches available to them in terms of feeding. Mycorrhizal species are most diverse in mixed woodlands containing a variety of trees that form mycorrhizal associations as not all trees do this. In Mirkwood Oak (Quercus) Birch (Betula) Alder (Alnus) and Hazel are all Ectomycorrhizal, Rowan (Sorbus) rarely and Ash (Fraxinus) is not.

As a result we find that 38% of the species recorded are mycorrhizal. Birch was recorded with most ectomycorrhizal species (19) with Alder supporting (14), Hazel was found to have (9) and oak (1).

Table 3. Feeding relationships of the fungi in a woodland ecosystem.

Species that are specific for their particular partner:

Birch; Amanita betulae, Amanita crocea, Lactarius glyciosmus, Lactarius pubescens, Lactarius torminosus, Leccinum scabrum, Russula betularum, and Tricholoma fulvum.

Oak; Lactarius quietus.

Hazel; Lactarius pyrogalus, Leccinum pseudoscabrum.

Alder; Paxillus rubicundulus, Cortinarius alnetorum, Cortinarius helvelloides, Russula pumila, Naucoria escharioides, Naucoria scolecina and Naucoria subconspersa.

Wood, particularly dead wood is the substrate for lignicolous fungi and the more dead wood there is the greater the diversity of these fungi. Like the mycorrhizal species some are specific in their requirements and very often are to be found growing on a particular type of wood, but most are not particular and will feed on a variety of different hardwoods. There is a considerable amount of dead wood in Mirkwood resulting in 44% of the fungi recorded being lignicolous and representatives occur in most of the different groups.

Some lignicoles that tend to have a preference for growing on particular types of wood:


– Fomes fomentarius, confined to Birch in Northern England but also found on Beech and occasionally other hardwood further south.

– Fomitopsis betulinu, Specific for Birch            

– Annulohypoxylon multiforme, mostly on Birch but can occur on other trees


– Daldinia concentrica, almost always on dead Ash and rarely on Beech.


– Hypoxylon fuscum, its preferred host is Hazel but can be found on Alder 

– Hydnoporia corrugate, The Glue Crust  gets its name from its habit of spreading  from one tree to another by gluing together twigs that are in contact most commonly this is Hazel.


– Mensularia radiata, Nearly always found on dead Alder trunks

– Pholiota alnicola; Occurs on dead or dying Alders

The species of terrestrial fungi recorded was small compared with the mycorrhizas and lignicoles accounting for 13% of the total number of species. Most of these are widespread and commonly occur in a variety of woodlands recycling dead leaves, some however as was found in Mirkwood occur in the general leaf litter but are quite specialised as to the substrate on which they feed.

Hymenoscyphus fructigenus or Nut Disco as its name suggests is a cup fungus that grows as a saprotrophe on fallen beech nuts and acorns it was recorded on both substrates.

Hymenoscyphus fraxineus. Although very similar to H. fructigenus the recording of this fungus is much more sinister. Found growing on the blackened leaf stalks of fallen ash leaves on the floor of the wood these are the fruiting bodies of Ash Die Back.

Tolypocladium ophioglossoides. Growing as small black clubs emerging from leaf litter this fungus is in fact arising from an underground False truffle Elaphomyces on which it is parasitic. Several species of Elaphomyces occur but on this occasion we were unable to locate the fruit body.

Onygena equina. Although not recognised as a regular part of the terrestrial mycota of woodlands The Horn Stalkball was recorded growing on the horns of a dead sheep. This is a rarely seen fungus despite the large number of sheep that graze throughout the county, it is very specialised in that it has the armoury of enzymes needed to feed on Keratin the substance of horns and hooves.

My thanks to all who were involved in this project.

Contributors included;

Stuart Colegate, David Clarke, Caroline Warlow, David Benham, Betty king, Chris Battersby, Audrey Battersby, Helen Hammond, Paul Nichol

Paul Nichol January 2021

* D. Bailey, J. Bailey, K. Davies, V. Davies, L. Hayward, M. Jordan, & P. Nichol, 2015. Fungus Conservation Trust Red List of Fungi for Great Britain, Lists 1-7

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