Bryophytes : Liverworts and Mosses 



473 



Mosses, therefore, show some advances over the liverworts 

 in their upright radial stems and branching rhizoids, in the regular 



Fig. 289. Mosses: A, Bryum, showing leafy gametophyte with attached sporophyte; 

 B, sporangium enlarged, showing the peristome teeth; C, details of peristome teeth. 

 D, Andrcea, showing leafy gametophyte and sporophyte with two sporangia; the one at the 

 right has shed its spores. E, germinating spore and protonema of a moss, showing bud from 

 which a leafy gametophyte develops. {After Frank.) 



occurrence of simple leaves, and in their ability to grow in drier 

 habitats. 



Life history of the moss. Mosses reproduce freely by vegeta- 

 tive propagation and by spores. A study of each of these meth- 

 ods will make clear the somewhat complicated life history of the 

 moss plant. 



Vegetative multiplication. When a moss spore germinates on 

 the soil, it produces a branching, filamentous body, the protonema 

 (Greek : protos, first, and nema, thread), which resembles some of 

 the branching forms among the green algae. The protonema 

 spreads over the soil for some distance and then develops numer- 

 ous buds (Fig. 289). The buds give rise to the upright leafy 



