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Fungus of the month

St George's Mushroom

Distinctive fungi to look for each month

by John Haughton

John is a volunteer with the Corby Woodland Project and Wildlife Trust BCN. He volunteers in the three areas of ancient woodland in Corby, but spends most of his time in King’s Wood close to where he lives. He has led several guided walks for Rockingham Forest Vision, sharing his enthusiasm for fungi. On these pages, as the months go by, he describes some of the most significant fungi that you may find in the wooded areas of Rockingham Forest.

April  – St George's Mushroom
- Calocybe gambosa


This mushroom gets common its name from the fact that this spring fungus appears towards the end of April each year, and is one of the earliest of the ground dwelling fungi to fruit. It is usually found in quite rich soils often in areas rich in limestone, and is found in grasslands (including gardens, parks, coastal grasslands) or deciduous woodland edges.

This firmly fleshy, whitish species has a white stem, off white domed cap and crowded, white gills. The spore print is also white. The cap can reach up to 11 cm and the whole fruit body smells strongly of flour.

Calocybe gambosa - St George's Mushroom 2.jpg
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The ‘fairy ring’ in grassland shown in this picture was about 2 metres across and on a wide verge of Gainsborough Road on the edge of Kingswood Estate in Corby.


All the others were taken in two areas of King’s Wood, Corby where they have fruited, to my knowledge, for the past ten years.

If you come across upon a small troop, look carefully because you may find that they're part of a much larger 'fairy ring'. These circles can grow many metres wide, and will usually re-appear in the same spot each year. In woodland look carefully because the ‘fairy ring’ may be partially hidden by undergrowth


May  – Two Ganoderma species
- Bracket Fungi

Ganoderma are often-inconspicuous fungi, normally growing low down on the trunk of broadleaved trees. There are two main species, Ganoderma applanatum and Ganoderma australe. They are typically thick, large (they can grow to about 60 cm across), semi-circular brackets that are also tough and woody. The flat topside can become quite knobbly with concentric ridges and is usually dark brown or reddish. The underside is white and easily scored, allowing drawings to be scratched into its surface.

The picture here is of a Ganoderma fungus on a log in King’s Wood with its characteristic brown spores  covering the leaves beneath the fungus.


The use of the fungus as a drawing material is what gives the Ganoderma applanatum its common name of Artist’s Bracket. There is a picture of this use on this Wikipedia page

Another feature of Ganoderma that I came across in King’s Wood and which I found quite fascinating was a very clear example of gravitropism. Gravitropism is the growth of a plant or a change in the direction of its growth in response to gravity.  Fungi display gravitropism of their fruiting bodies which is thought to facilitate spore dispersal. The spore surface whether pores or gills are in the horizontal plane, allowing the spores to drop vertically down.

These two pictures were taken in December 2013 and show a large ash tree, recently blown down by the wind. The red arrow indicates a large Ganoderma fungus about 70 cms across with its spore surface now vertical instead of  horizontal.

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The two species are impossible to identify with certainty without microscopic examination of spores. However, if you find a bracket with the galls of the Yellow Flatfooted Fly (Agathomyia wankowiczii) on its lower surface, then you know you have Ganoderma applanatum, on which the fly lays its eggs. It does not lay them on Ganoderma australe.

These two pictures show Ganoderma applanatum with Yellow Flat Footed Fly galls that I have found  in King’s Wood


These two pictures were taken one year later in November 2014. It can be clearly seen where small bracket fungi have grown out of the upper surface of the original fungus allowing the new spores to be dispersed, because the original fungus spore surface cannot release spores due to its new vertical position on the fallen tree.


It is also interesting to note that the Ganoderma fungus most probably played a significant part in creating the decay, that weakened the tree, allowing it to fall, thereby causing the fungus to be unable to release its spores.

June – Sulphur Tuft
- Hypholoma fasciculare


This is the first group of Sulphur Tuft I’ve seen this year. A not very exciting scene in King’s Wood early in May during the RFV walk led by Ana Pirez, looking at tree pests and diseases .  The fungi were growing on a very rotten stump. The second picture shows the gills and remnants of the veil.

Sulphur Tuft mainly appear on dead wood and are part of the wood-decay process: they will happily help to decay both hardwood trees and conifers. The cap of the fungus is a sulphurous yellow, often being more tan coloured towards the centre of the cap. There are sometimes dark remnants of the veil that had covered the gills, remaining on the cap margin.  The gills of this fungus are initially sulphur yellow, becoming olive-green and gradually blackening as the spores ripen.

Here is a more photogenic group.

This is a large troop of Sulphur Tuft fungi on a fallen oak in King’s Wood. They appeared on this log for two or three years in succession, but none since. The log is about 6 metres (20 ft) long.

There is another very similar fungus, the Conifer Tuft - Hypholoma capnoides, which as its common name suggests, only grows on decaying conifer wood. The Conifer Tuft is very similar to the Sulphur Tuft except that the gills do not have the greenish tint that Sulphur Tuft has.

Getting started with fungi in Rockingham Forest

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