Tree Cross Section

From a year ago: a cross section of a beech tree (Fagus sp) that has been attacked by the fungus Auricularia mesenterica (see here for some close-up photos of the actual fungus).  

Originally the cross section would be all brown but the fungus has digested the hard brown lignin from all but the left and lower left margins leaving most of the cross section whitish.  The dark linear markings appear to be lines of defence where the tree attempted to seal off the advance of the fungal hyphae.

Photo taken in the Wilderness, Whiteknights Park, Reading, UK, on 2013-02-25.