SOME FUNGI IN WOOD.
37
fungi in their substratum and upon their effects upon this sub~
stratum, wood. A glance at the species mentioned makes it
apparent that the majority are Basidiomycetes with the bracket
type of sporophore, and also that the Polyporaceae are very well
represented. The bracket type of sporophore is, of course, to be
expected, rather than the mushroom type, in fungi which
"fruit" on trees and posts, although the mushroom type is
represented by forms like Pholiota.
The Polyporaceae will be dealt with first.
Polyporus sulphureus (Bull.) Fr., attacks standing timber, both
broad-leaved and coniferous, and is a widespread species,
occurring both in Europe and North America: Eades [9] regards
it as more troublesome in broad-leaved trees, although, according
to HiIey [18], it appears to be more general on conifers in North
America, but in Britain it is more frequent on the oak. The
fungus is responsible for a brown cubical rot in the heartwood
of the tree, and is a wound parasite, obtaining entry where the
heartwood is exposed, as, for example, where large branches
are broken off; in reference to oak, Cartwright and Findlay [8]
point out that old parkland trees are more liable to attack than
plantation trees, because the large side branches of the former,
which, of course, are absent in plantation timber, are liable to
be broken off by the wind and thus expose the heartwood to
attack. The fungus is not restricted to the living tree, but will,
given suitable conditions, continue its growth in felled timber,
and appear in structural timbers, although it would seem that
infection is restricted to the living tree. Incipient stages of
the rot result in the development of a pale brown colour,
but this does not appear until some time after the hyphae of the
fungus are in the wood; the colour becomes reddish brown in
advanced decay, and the appearance of radial and tangential
clefts in the wood result in the characteristic cubical rot; the
cracks become filled with fungus hyphae of a yellowish
colour. The wood becomes brittle and easily powders on slight
pressure.
Polyporus Schweinitzii Fr. is confined to coniferous timber,
and occurs both in Europe and in North America. Like the
last, it is a cubical brown rot of the heartwood, but is confined to
the lower parts of the tree—it is a root and butt rot, and seems
rarely to extend far up the trunk. There seems to be some