272 



PEACTICAL BOTANY 



the leafy liverworts from some of the mosses except when the 

 sporophytes are present. In one group of liverworts, of which 

 the horned liverwort (^Antlioceros) is the commonest represent- 

 ative, the gametophyte is strikingly simple and the sporophyte 

 equally striking in its complexity (Fig. 227). This plant is 

 widely distributed upon damp rocks, banks of streams, and often 

 in open meadows. The gametophyte is small and extremely 



thin. The simple antheridia 

 and archegonia are embedded 

 in the gametophyte. After the 

 oospore is formed, it germi- 

 nates and produces a sporo- 

 phyte, which consists of a 

 large swollen foot region and 

 prominent stalk. The foot is 

 well fitted to absorb nourish- 

 ment from the gametophyte 

 and the stalk bears chlorophyll. 

 The presence of stomata in the 

 stalk further suggests ability 

 to do chlorophyll work. In- 

 deed, if the sporophyte could 

 live with its foot in the soil, 

 it might live independent of 

 the gametophyte. The entire 

 stalk becomes a kind of cap- 

 sule, part of its tissues forming 

 spores, first at its tip, then lower and lower down to the base. 

 It is the supposed resemblance of the sporophyte to a horn 

 which gave the name horned liverworts to the Anthoceros forms. 

 254. Summary of the bryophytes. The bryophytes are in 

 many respects higher plants than the thallophytes. Sexual 

 reproduction by means of complex archegonia and anther- 

 idia occurs upon one phase of these plants, and asexual 

 reproduction by means of special capsules occurs upon a dis- 

 tinctly different part of the plant's life cycle. This constitutes 



-- 9 



r 



FIG. 227. Anthoceros, a liverwort 

 with very simple thallus and com- 

 plex sporophyte 



