Mar,, 1911.] The Classification of Plants, VI. 291 



5. From choripetalous to sympetalous, apetalous or naked 

 flowers. 



6. From spiral to actinomorphic flowers, and further to 

 isobilateral, unsymmetrical, or zygomorphic types. 



7. From bisporangiate to monosporangiate and further from 

 monecious to diecious flowers. 



S. From types with all the organs normal to those that show 

 vestigal parts. 



These developments are repeated again and again. Certain 

 of these specializations show themselves even in primitive grotips. 

 In many cases no relation with the environment is evident, but 

 advancing tendencies apparently originate in the internal consti- 

 tution of the plant itself. Thus we are led to recognize tendencies 

 which may or may not come to expression in the diverse species of 

 a natural group. The whole phylogenetic development bears a 

 close resemblance to the ontogenetic expression of hereditary 

 characters in the individual. 



The development of the inflorescence is equally interesting 

 with that of the flower itself. In the primitive groups a single 

 flower tenninates a main vegetative branch and from this condi- 

 tion appear all gradations of reduction and clustering through 

 racemes, corymbs, and panicles to spikes, spadixes, catkins, heads, 

 and disks, and their various modifications. 



In general then, the process of segregation, classification and 

 arrangement should proceed on the following basis: 



1. Development of the floral organs. 



2. Specialization and degeneration of the floral parts. 



3. Specialization and degeneration of the vegetative parts. 

 The segregation must be fundamentally phyletic and should 



follow a recognition of the gaps produced by variation, mutation, 

 and the destruction of intermediate types, while the arrangement 

 in series should follow the evolutionary progression as indicated 

 by comparative morphology and complexity of life cycle, together 

 with the presence of vestigial parts. Vestigial organs are of the 

 highest importance in any classification of the angiospenns 

 because of their common occurrence. It is necessary, therefore, 

 to be able to distinguish vestigial organs or vestiges from nascent 

 organs or primordia. Paleontological evidence would here be of 

 paramount importance but satisfactory fossil flowers are too rare 

 for our purpose. 



Before taking up the special question of the relationships in 

 the Anthophyta a word may be said in regard to the importance 

 of synopses. The synopsis is commonly confused with a key for 

 identification. A synopsis should show the supposed phyletic 

 relationship; a key should be the easiest means for ascertaining a 

 name whether of group or species. In most cases the synopsis 

 does not make a satisfactory, working key. The genera of 



