TIIK PKAT MOSSES 



291 



peat mosses arise from special buds. These cell plates suggest 

 the simple thallnid gametophytes of the liverworts, and the leafy 

 structure is perhaps a special development from them. 



The peat mosses live in bogs and swamps and are especially 

 common in northerly regions and in the mountains, where they 



FIG. 200. The sporophyte of the peat moss (Sphagnum) 



A, group of the sporophytes on stalks, which are really growths from the game- 

 tophyte. B, longitudinal section through a sporophyte, showing the large foot 

 imbedded in the top of the stalk: a, the remains of the parent archegonium, 

 with the neck still present ; s, spore chamher ; c, cover 



grow over wet rocks, sometimes covering large areas. They 

 develop so rapidly that they frequently fill ponds and bogs. 

 The first growth is around the edges of the pond, but this grad- 

 ually works inward, until' finally the whole surface is covered 

 with peat moss. Such conditions produce quaking bogs, for the 

 surface is not firm enough to hold any large animal which 

 might walk upon it. Quaking bogs become firmer as the lower 



