THE GKEAT GEOUPS OF BRYOPHYTES 
319 
Mosses, which are sometimes called the Bryum forms, to 
distinguish them from the Sphagnum forms. They are 
the representative Bryophytes, the only group vying with 
them being the leafy 
Liverworts, or Junger- 
mannia forms. They 
grow in all conditions 
of moisture, from actual 
submergence in water to 
dry rocks, and they also 
form extensive peat de- 
posits in bogs. 
The sporogonium has 
a foot and Usually a long FlG< 292 - Sporogonia of Grimmia, from all of 
which the operculum has fallen, displaying 
Slender Seta, but the Cap- the peristome teeth: A, position of the teeth 
SUle is especiallv COm- when dr y ; s > Position when moist. After 
KERNER 
plex. When the lid-like 
operculum falls off, the capsule is left like an urn full of 
spores, and at the mouth of the urn there is usually dis- 
played a set of slender, often very beautiful teeth (Fig. 
292), radiating from the circumference to the center, and 
called the peristome, meaning " about the mouth." These 
teeth by bending inward and outward help to discharge the 
spores. 
