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 dieeious flowers. 
8. 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 groups. 
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 terminates 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 angiosperms 
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 
