THE ANTHOCEROS GROUP 



289 



which higher plants must have arisen 

 from forms somewhat like the liver- 

 worts, a subject which we shall con- 

 sider later in our account of the ferns 

 (Sec. 331). Of all the bryophytes, 

 this seems to be the genus which 

 most closely approaches the higher 

 plants. This account of plant evo- 

 lution is now well started towards 

 the higher conditions of plant devel- 

 opment, namely, those of the ferns 

 and seed plants whose : sporophyte 

 generations are independent plants 

 with roots, stems, and leaves, and 

 which comprise the most independ- 

 ent and successful vegetation on the 

 earth. 



CLASS II. THE MOSSES, OE 

 MUSCI 



291. The mosses. The mosses are 

 very much more numerous than 

 the liverworts. Some of the com- 

 mon kinds grow in extensive carpets 

 on hillsides and in forests, becom- 

 ing important factors in the plant 



A, longitudinal section (semi-diagrammatic) 

 through the base of the sporophyte, showing 

 the large foot imbedded in the tissue of the 

 gametophyte, the region of growth, and the 

 spore-producing tissue which forms a cylin- 

 der in the center of the stalk ; B, a group 

 (tetrad) of four spores (three shown) in a 

 spore mother cell; C, spores; D, a stoma 

 viewed from the surface ; E, section through 

 a stoma, showing cells with large single 

 chromatophores under the surface layer 

 (epidermis) 



B 



FIG. 268. The sporophyte of 

 Anthoceros 



