ANGIOSPERMAE 117 



We are consequently forced to draw our conclusions 

 almost entirely from the existing vegetation, and here 

 recent investigations render it feasible to trace the mono- 

 cotyledons back to some primitive member of the group 

 Poly carp icae (Ranales). There are various features in 

 the anatomy of roots and stems, as well as in the structure 

 of the sexual organs of Nymphaeaceae and other 

 members of the group Polycarpicae, which support the 

 view that the ancestors of the present Helobiae originated 

 from some primitive member of that group, and that the 

 monocotyledons consequently are a lateral, although very 

 early branch of the dicotyledonous main line of development. 



No linear arrangement of groups, such as a book 

 demands, can do full justice to their genetic sequence ; 

 but the insertion of the monocotyledons immediately after 

 the gymnosperms would interrupt the natural sequence of 

 the groups to such an extent that this fairly independent 

 branch is better referred to the end of the system*. 



In order to express the views prevailing at the present 

 time on these questions we venture to append the rough 

 diagram overleaf, which, it must be well understood, is to 

 a large extent hypothetical, for speculation has still a wide 

 field in these matters. 



* For a fuller discussion of the subject see (i) Coulter and Chamberlain, 

 Morphology of Angiosperms; (2) Fritsch, Die Stellung der Monocotylen, Leipzig, 

 1904; (3) Rendle, Classification of Flowering Plants, Vol. 1, Cambridge, 1904; 

 (4) Wettstein, R. von, Handbuch der Systematischen Botanik. Second Edition. 

 Vienna, 191 1. 



