50 INTRODUCTION TO PLANT GEOGRAPHY [CHAP. 



is a regular alternation of gametophytic and sporophytic generations, 

 such as we shall see later in all normal higher plants. Though the 

 gametophyte tends to be more evident and ' dominant ', these 

 generations in the Liverworts have no independent existence, and 

 consequently their dual significance is somewhat difficult to grasp. 

 Both generations are depicted in each of the different types of 

 Liverworts shown in Fig. 13. 



A_ 



B ^ 



Fig. 13.— Types of Liverworts (Hepaticae). A, Marchantia, a thalloid type, 

 showing female plant on left and male on right (x lA); B, C, leafy Liverworts 



(B, X 4; C, X i). 



