CHAPTER X. 



BRANCH IV. BEYOPHYTA. 



THE MOSSWORTS. 



380. This branch includes plants of much greater com- 

 plexity than any of the preceding. In very many cases 

 they have distinct stems and leaves, whose tissues often 

 show a differentiation into several varieties. In the sexual 

 organs the cell to be fertilized (the germ-cell) is from the 

 first enclosed in a protective layer of cells, and after fer- 

 tilization it develops into a complex spore-fruit. 



381. The life-cycle of the Mossworts includes a marked 

 alternation of generations. The immediate product of the 

 fertilization of a germ-cell is not a thalloid or leafy plant 

 like that which bears the sexual organs, but, on the con- 

 trary, it is a many-celled leafless structure, spherical or ap- 

 proximately cylindrical, which eventually produces spores. 

 The plant which produces the sexual organs is the sexual 

 plant (gametopliore or gametophyte) while that which pro- 

 uces the spores is the asexual plant {sporophore or sporo- 

 phyte). 



382. Mossworts are all chlorophyll-bearing plants, and 

 none are parasitic or saprophytic. They are of small size, 

 rarely exceeding ten or fifteen centimetres in height. 

 They generally prefer moist situations upon the ground, or 

 on the sides of trees or rocks. A few are aquatic. Two 

 classes may be distinguished, as follows : 



Mostly thalloid creeping plants, usually witli splitting spore-fruits, 

 and having elaters Class 9, Hbpatic^ 



LeaCy stems, mostly erect, witli spore-fruit usually opening by a lid, 



and having no elaters Class 10, Musci, 



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