278 



Science of Plant Life 



Fig. 163. Mosses, showing the compact grouping of the plants. 



condition; and when wet, they go on with their normal 

 processes of photosynthesis, respiration, growth, and repro- 

 duction. 



Mosses also possess means of anchorage by rhizoids. The 

 rhizoids of the Hverworts are one-celled structures. Those of 

 the mosses are branching, many-celled structures which pene- 

 trate the soil, affording a firm hold and absorbing a part of 

 the water used by the plant. The habit of growing in com- 

 pact clusters gives the mosses a method of conserving water 

 and maintaining the water balance, other than the methods 

 spoken of in connection with the liverworts ; the dense masses 

 of plants take up water from rains and hold it for some time 

 like a sponge. 



Mosses, therefore, show some advances over the liverworts 

 in their upright stems and branching rhizoids, in the regular 

 occurrence of simple leaves, and in their abihty to grow in 

 drier habitats. The liverworts and mosses together show the 



