CHAPTER XLVin 



MOSSES AND LIVERWORTS 

 (BRYOPHYTES) 



Mosses and liverworts grow throughout the world, from the high moun- 

 tains of Antarctica to northernmost Greenland. Species of moss occur in 

 nearly every habitat, from 180 feet under water in a Swiss lake to the 

 driest deserts of Arizona. Liverworts grow in less extreme situations but 

 in a surprising variety of them. Neither the mosses nor the liverworts live 

 in sea water. 



Bryophytes are common in the vegetation on the arctic and alpine 

 tundra (Fig. 292). They are most abundant in moist and wet situations. 

 Bryophytes are also abundant in the north woods and in the moist 

 forested regions of the Pacific coast (Fig. 293). There they and the 

 lichens not only live on the soil and on the trunks and branches of living 

 trees, but they soon cover the fallen trees with a living green spongy 

 mantle, beneath which the relentless processes of disintegration proceed 

 ( Fig. 294 ) . Mosses form the primary mats of the floating and semi-solid 

 substrates of bogs and "muskegs." Held together by the tangled fibrous 

 roots of sedges, ferns, and shrubs, they grow above and die below, thus 

 contributing to the gradual filling of depressions and lake basins with 

 peat. 



Clearing of the forests and cultivation of the land by man have de- 

 stroyed numerous habitats of many kinds of bryophytes in agricultural 

 regions. But these species may still be found in rock gorges, swamp 

 woods, and other forest remnants where they have survived and are 

 often locally abundant. On the other hand, some species are more 

 abundant in partially cleared forests, and a few may be found in culti- 

 vated fields. 



The grasses of old shaded lawns are often replaced by several species 

 of mosses and liverworts. Examination of clover fields and pastures will 

 reveal a surprising carpet of these little plants growing with the soil 

 algae. When farms are abandoned, bryophytes are among the pioneer 

 invaders of "worn-out" soils. Years later, when young woodland has occu- 



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