THE 
HEW PHYTOIiOGIST. 
Vol. XI, Nos. 5 & 6. 
May & June, 1912. 
[Published June 24th, 1912]. 
FLORAL EVOLUTION : WITH PARTICULAR REFERENCE 
TO THE SYMPETALOUS DICOTYLEDONS. 
By H. F. Wernham. 
■t 
VI. Tetracylid/E : Part III. Tubiflor/E (concluded). 
R. MOSS, in a recent series of lectures on the principles of 
classification of the Angiosperms, 1 made the remark that 
the question whether the allied orders of Contortse, Tubifloras and 
Plantaginales have any relationship with Archichlamydeae, or 
whether they have diverged from the other sympetalous forms, is 
the outstanding problem of the Sympetalae at the present time. 
The key to the solution of this problem seems to lie in the origin of 
the Contortas; and we have endeavoured already in these papers 
to attack this question, and to find some support for the view that 
this cohort, like those comprising the Pentacyclidae, is derived 
from a polypetalous stock. This once established, the origin of the 
Tubiflorae will not be far to seek; its connection with Contortae by 
way of our so-called “Transitional Group” has been urged in the 
last chapter. It is the object of the present chapter to add the 
remaining links in this evolutionary chain by tracing the connection 
between this last-named group and the higher Tubifloras—the 
Personales and Lamiales of Bentham and Hooker—and between 
the latter and Plantaginales. 
The prime distinction between the higher Tubiflorae and the 
Transitional Group lies in the character of zygomorphy coupled 
with oligomery of the androecium; the regular flower with iso- 
merous androecium is very rare among the members of the groups 
which we are about to consider. In the latter, as already indicated 
at the beginning of the last chapter, the fundamental tendencies in 
respect of economy and adaptation to insect-visits stand fully 
1 Delivered at University College, London University, during 
Michaelmas Term, 1911. 
