DIVISION III. 

 BRYOPHYTA. 



CHAPTER XXX. 



MUSCI AND HEPATICAE : MOSSES AND LIVERWORTS. 



The Bryophytes include two Classes, represented by very numerous 

 species, widespread in all lands except in those of persistent drought. 

 They are the Musci or Mosses, and the Hepaticae or Liverworts. 

 These form a very natural alliance, and indeed are distinguished from 

 one another only by minor characters. Everyone knows the general 

 appearance of Mosses, as low-growing leafy plants, chiefly found in 

 moist surroundings. The Liverworts, with a similar habitat, have 

 commonly a flattened form described as a thallus ; but some of 

 them bear small leaves. Thus the Bryophytes may be either leafy or 

 thalloid. All the Bryophytes show a cycle of life of the same general 

 plan, having two alternating generations. That green and often 

 leafy structure which is recognised as the " Moss or Liverwort- Plant " 

 turns out on examination to be the gametophyte. It bears the sexual 

 organs, while the sporophyte, which is produced from them and 

 bears the spores, is the well-known Capsule, or Sporogonium (Fig. 355). 

 In all the Bryophytes the spore-bearing generation is dependent upon 

 the gametophyte throughout its existence. It never fixes itself 

 directly in the soil. Thus the leading morphological feature is the 

 relatively high vegetative development of the sexual generation, which 

 is able to carry on active nutrition and propagation, and commonly 

 persists as a perennial. There is no elaborated root-system. It 

 is true Mosses and Liverworts have rhizoids ; but both depend for 

 their water-supply not only upon localised absorption by these, but 

 also upon general absorption by their whole surface, as opportunity 



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