TAXONOMIC PRINCIPLES 25 



tern as are the treatments in numerous floras and texts. Engler's system 

 is not ordinarily displayed in schematic form, mainly because its author 

 did not claim his treatment to be phylogenetic (Turrill, 1942), and the 

 system is recognized by most taxonomic workers as a useful but 

 partly artificial arrangement, 



2. BESSEY SYSTEM 



Bessey was one of the most astute and prolific American 

 taxonomists to put forward a system of classification for the higher 

 plants. His system (Fig. 2.8) differed considerably from that of Engler 

 in that, instead of emphasizing progressive specialization from the 

 superficially simple flowers of both monocots and dicots, such as Engler 

 proposed, Bessey felt that progressive diff"erentiation has proceeded 

 along a number of lines, one of these being the loss of parts from a 

 relatively simple but multicarpellate perfect flower such as is found 

 in the families Ranunculaceae and Magnoliaceae. This system was 

 not elaborated nearly to the degree that Engler's system was, and, in 

 addition, it suffered certain shortcomings resulting from the fact that 

 Bessey had only fragmentary knowledge of the families indigenous to 

 other parts of the world. In any case, Bessey's system did not receive 

 wide acceptance outside of the United States, although, as is apparent 

 from the Hutchinson system (discussed below), the principles on 

 which Bessey's system was erected have received wide approval 

 elsewhere. 



3. HUTCHINSON SYSTEM 



Hutchinson's system of classification for the flowering plants 

 was formulated on about the same principles as Bessey's system with 

 one important exception: Hutchinson thought that there occurred 

 early in the evolutionary history of the group a major phyletic di- 

 chotomy, resulting in an herbaceous offshoot which produced both the 

 herbaceous dicots and the predominantly herbaceous monocots of 

 today. The ancestral woody plexus was believed to have given rise to 

 those dicot families with mainly woody species. When the herbaceous 

 habit is found in otherwise essentially woody families such as the 

 Leguminosae, it is assumed by Hutchinson to have an independent 

 origin. The same is believed to be true for those semi-woody groups 

 which occur in essentially herbaceous families (for example. Clematis 

 in the Ranunculaceae). 



Hutchinson's scheme allows for the wide separation of what 

 heretofore have been looked upon as fairly closely related taxa (for 

 example, the Umbelliferae and Araliaceae; see Baumann's phyletic 

 diagram for these groups. Fig. 2-3). Hutchinson ascribes much of this 



