THE 
HEW PflYTOIiOGIST. 
Vol. XI, No. io. December, 1912. 
[Published Dec. 31st, 1912]. 
FLORAL EVOLUTION : WITH PARTICULAR REFERENCE 
TO THE SYMPETALOUS DICOTYLEDONS. 
By H. F. Wernham. 
IX. —Summary and Conclusion. Evolutionary Genealogy ; 
and Some Principles of Classification. 
W E have completed our review of the several sympetalous 
groups ; and it may be well now to summarize briefly the 
facts to which reference has been made, and the conclusions which 
have been drawn therefrom. 
We have from the outset, however, proceeded on the assumption 
that Sympetalse have been derived from polypetalous ancestors, 
and we must examine the justification for this assumption before 
we proceed further. 
The origin of the Angiosperms is one of the leading problems 
of systematic botany, and one of the farthest from solution. It is 
not improbable that the Dicotyledons and Monocotyledons have 
diverged from a common proangiospermous ancestry, neither being 
derived from the other (see fig. p. 385); but the question now 
before us is, whether the polypetalous and the sympetalous series 
of Dicotyledons stand in a similar mutual relation, or whether 
Sympetalas have been derived directly from Polypetalse in the 
continuous course of evolutionary descent. 
Have Sympetal,e necessarily descended from polypetalous 
Dicotyledons ? 
All the considerations which we have exhibited in the foregoing 
chapters point to the affirmative answer to this question with almost 
irresistible force. All the biological tendencies of floral evolution 
which we have traced are strongly suggestive of the phyletic 
continuity between polypetalous and sympetalous forms, and go to 
justify the name Archichlamydece, primitive perianths. The fusion 
