THE OREAT fiKOUPS |-)F RKYorilYTES 



n9 



Mosses, wliich arc sometimes called the Hryum forms, to 



distinguish them from the Hphafjiiuia forms. They are 



the representative Bryophytes, the only group vying with 



them l)eiiig the leafy 



Liverworts, or Junger- 



munnia forms. They 



grow in all conditions 



of moisture, from actual 



submergence in water to 



dry rocks, and they also 



form extensive peat de- 



jiosits in bogs. 



The sporogonium has 

 a foot and usually a long 

 slender seta, but the cap- 

 sule is especially com- 

 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 perisfoiiie. meaning " al)out the mouth." These 

 teeth by bending inward and outward helja to discharge the 

 spores. 



Pig. 292. Sporogonia of Onmmia. from all of 

 which the opercuhiin has fallen, dhsplaying 

 the peristome teeth: .1, position of the teeth 

 when dry ; B. position when moist. — After 

 Keenkk. 



