FUNGI 155 
tures commonly called mushrooms are the spore-bearing 
branches. In pulling up a mushroom, fragments of the 
mycelium may often be seen attached to it, looking like 
small rootlets. In the following description, however, the 
word mushroom will be used in its ordinary sense. 
The mushroom has a stalk-like portion (st¢pe) and an 
expanded umbrella-like top (pileus). On the under side of 
the pileus there are found thin, radiating, knife-blade-like 
plates (gills) (Fig. 147, A). The surface of the gills consists 
of a layer of peculiar club-shaped cells called basidia (Fig. 
147, B). From the broad end of each basidium usually 
four delicate branches 
arise, each producing at 
its tip a minute spore 
(Fig. 147, C). The ripe 
spores shower down from 
the gill surfaces, germinate, 
and produce new mycelia. 
The most common edi- 
ble mushrooms grow in 
fields and pastures; but 
there are numerous mush- 
rooms in the deep woods, 
in fact wherever there is 
decaying organic material. 
It has been found impos- 
sible to give directions for MS Fe 
distinguishing edible and 
RB Fic, 148.—A common pore-fungus.— 
poisonous forms that can “Attar GIBSON: 
be used by those who are : 
not familiar with mushrooms. It is exceedingly unsafe for 
an inexperienced person to gather wild mushrooms for eat- 
ing, for some of the deadliest forms resemble in a general 
way those commonly eaten. 
The mushrooms with gills form a very large group, 
