Bottle butt on oak from Pseudoinonotus dryadeus

First and foremost, I wish to extend a thank you to David Humphries for confirming that what I was looking at here was Pseudoinonotus dryadeus. Given the condition of the (significantly lacking) brackets, I had only anticipated them being P. dryadeus because of the algal greening atop their structure, though having not seen this fungus in abundance it was very much an ‘educated’ guess.

The below pictures taken of the desiccated brackets around the butt of an oak (which sits on a woodland edge next to a golf course) are very telling. Classic bottle butt associated with a white rot (in this case, it is a selective white rot) can be seen, and consulting the very brilliant Arborist’s Field Guide by Guy Watson and Ted Green, the buttressing present here is indeed indicative of P. dryadeus decay. The authors state: “many trees stand on ‘stilts’ of buttress roots where the fungus has decayed the central wood completely, giving the appearance of the Eiffel Tower.”

Of course, failure is a risk. If decay extends into the buttress zones, or the buttresses have been weakened via other means, then windthrow may be of a higher possibility. Given this oak is a woodland edge tree, and the target zone beneath is frequently used (particularly in summer), management of the hazard via means of pruning may very well be something to consider.

Very distinct buttressing can be observed at the base of this oak, and some discernible reaction growth can be seen on the right side of the butt just above the buttresses. Remnants of three different sporophores can be seen (two on the left and one in the centre).

A closer inspection shows how deep the buttresses go around the region where sporophores can be identified.

Looking at an individual sporophore shows the rust-coloured flesh and algal greening atop – both suggestive of P. dryadeus in its desiccated form.

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