Liverworts and Mosses . 281 



The first stage in the life history of the plant ends with 

 the production of oospores. The second stage ends with the 

 formation of asexual spores. When the asexual spores germi- 

 nate, they again produce the protonema and the leafy moss 

 plants. The asexual spores are small, firm-walled, rounded 

 bodies that are able to withstand the drying effects of the 

 air. They are fitted to be blown about, and so to start the 

 growth of the plant in new areas. Most moss plants are 

 perennials, and they produce both oospores and asexual spores 

 on new branches for several years. 



Summary. Liverworts and mosses constitute a group of 

 rather simple land and amphibious plants. They are of par- 

 ticular interest because they show some of the steps by which 

 simple water plants become adjusted to conditions on land. 

 This group represents the most complex of the land plants 

 that lack a conductive system. In the next group, the ferns, 

 the plant has a well-developed water-conducting and food- 

 conducting system, and correlated with this it has greater 

 size and more complex tissue systems. 



