2148 



I. 



2. 



3- 

 4- 



5- 



A TEXTBOOK OF THEORETICAL BOTANY 



6. 



Sphaerocarpales 



Marchantiales 



Jungermanniales 



Anthocerotales 



Sphagnales 



7 

 8 



9 

 10 



Andreaeales 



Tetraphidales 



Polytrichales 



Buxbaumiales 



Eubryales 



This fusion of the two groups did not find much support among other 

 writers and we find that Dixon in his " Students' Handbook of the British 

 Mosses", and MacVicar in his " Students' Handbook of the British 

 Hepatics", pubhshed in 1896 and 191 2 respectively, and in the subsequent 

 later editions, retain the separation of the two groups from one another. 

 Their methods of classification, however, follow in the major groups the 

 system laid down by the Engler Syllabus. 



Classification is the subject of two articles in the " Manual of Bryology " 

 published in 1932, the one on the Mosses written by Dixon and the other on 

 the Hepaticae contributed by Verdoorn. The outline of these systems 

 is appended below and may be regarded as the most modern system of 

 classification. 



! 



THE PTERIDOPHYTA 



The classification of the Pteridophyta presents problems not en- 

 countered in any of the previous groups, due to their greater complexity 

 and diversity of structure. Within the group there are two separate trends 

 of divergence. The first is in regard to the relative size of the foliage and 

 the stem, one line tending towards relatively minute leaves, the other 

 towards leaves of increasing size. The second trend is to the appearance of 

 heterospory in certain groups. These two apparently fundamental features 



