328 PRACTICAL COURSE IN BOTANY 
while the favorite edible kind (Agaricus campestris), though 
white-gilled when young, produces dark, purple-brown spores 
that cannot fail to distinguish it clearly for any one who will 
take the trouble to make a print. 
378. Economic properties. — Most of the wood-destroy- 
ing fungi belong to this and allied orders. They are among 
the worst enemies the forester has to deal with (140), and 
millions of feet of 
lumber are destroyed 
every year by them. 
Over seven hun- 
dred kinds of fungi 
growing in the United 
States have been de- 
scribed as edible, but 
the evil repute into 
which the whole class 
has been brought by 
the poisonous quali- 
ties of a few species, 
ip ibe 
Fia. 468. — Portion of the root of a maple affected and the difficulty, to 
with rot caused by the mycelium of a fungus that any but an expert, of 
has penetrated to its interior. ee A ‘ 
distinguishing be- 
tween these and the harmless kinds, has caused them to be 
generally neglected as articles of diet. While they are 
pleasant relishes and furnish an agreeable variety to our daily 
fare, their food value has been greatly exaggerated. They 
contain a large proportion of water, often over 90 per cent, 
and the most valued of them, the Agaricus campestris, is 
about equivalent to cabbage in nutrient properties. 
Practical Questions 
1. Why are mushrooms generally grown in cellars? (186, 343.) 
2. Name any fungi you know of that are good for food or medicine or 
any other purpose. 
3. Name the most dangerous ones you know of. 
