FUNGI AND BEECH 231
of other broad-leaved trees, especially oak. This fungus
causes a heart-rot of beech. It is only old trees that are
affected, and the huge woody brackets, up to two feet
across, are found mostly towards the base of the main
trunk. Like other fungi causing heart-rot in standing
trees, the fungus can gain entry only through a wound. It
may be argued that such a fungus as this is not a parasite,
since, although it occurs on the living tree, it is utilizating
for food dead material, namely the heart-wood. Incidentally,
Ganoderma applanatum is one of the greatest spore-
producers of the fungal world. It has been estimated that
a large specimen liberates 20,000,000 spores a minute, and
this huge rate of output may be maintained more or less
continuously from May to October. If a fruit-body is
viewed closely on a sunny day, spores can be seen as motes
in the sunbeams, raining down continuously and drifting
away as ferruginous smoke.
Another large perennial polypore is Fomes fomentarius,
the Tinder Fungus (Plate 9). This is a common species
causing heart-rot of beech on the Continent. In this
country it is quite common in Northern Scotland, where it
attacks birch, but in England it is very rare. However,
I have found a number of beech trees at Knole Park in
Kent bearing magnificent specimens, but, so far as I know,
it is not found in Epping Forest. Many of the older records
of this species were made by mycologists who confused it
with Ganoderma applanatum. Fomes fomentarius has
hoof-shaped fruit-bodies, both its upper and lower surfaces
are grey, and it liberates clouds of white spores.
A number of other fungi are weak parasites of beech.
A conspicuous example is Armillaria mucida (Plate 9).
This usually occurs on branches of standing trees rather
than on the main trunk. The glistening white fruit-bodies,
often present in considerable numbers, make a very striking
picture. Unlike A. mellea, this species is found almost
exclusively on beech, although it is very rarely to be seen
on oak and birch as well. A. mucida agrees with A. mellea
in having a fruit-body with a well-defined ring and white
spores, but modern French workers prefer to place it in the
genus Collybia. Another gill-bearing weak parasite of
beech is the Oyster Fungus, Pleurotus ostreatus, and, like