420 FIRST FORMS OF VEGETATION. 
a portion is examined under the microscope, 
is seen to traverse the whole fabric of the wood 
with a beautiful net-work of minute threads, 
giving it the peculiar green tint which is so much 
admired. The fungus attacks fallen oak branches; 
but while it permeates the wood with its spawn, it 
seldom produces the little green open cups of its 
mature state, so that the origin of green wood is 
mysterious to the uninitiated. Of course, such 
timber being in a state of decay is worthless except 
for ornamental purposes. Gardeners frequently 
complain of the spawn of fungi destroying trees and 
herbaceous plants. Rhododendrons in shrubberies 
are often rendered sickly by a substance resembling 
sarsaparilla, or a mass of branched and corrugated 
roots about the thickness of a tobacco-pipe, travers- 
ing the soil and twisting round the roots of the 
shrubs an inch or two beneath the surface. This 
parasite is supposed to be an anomalous condition 
of some fleshy fungus, such as Agaricus grammo- 
cephalus, which is common in shrubberies, sending 
out its branched root-like strings in all directions 
to a great distance. Whenever the parasite is 
removed the shrubs recover their proper healthy 
character. Old hidden stumps and decayed roots, 
owing to the spawn of fungi which they contain, 
are peculiarly dangerous to young plantations. 
It is not always safe, for the same reason, to plant 
