Floral Evolution. 
383 
tendency is realized already in the descendants of the archichlamy- 
deous Umbellifloral Stock (Umbelliflorse), represented by Araliaceae 
in which each ovary-chamber contains regularly but one ovule. 
From this stock the Umbelliferse arose as the expression of the 
bicarpellary condition of the ovary and of fruit-specialization, 
together with Aggregate Zygomorphy. 
Before the evolution of the Umbellifloral Stock a sympetalous 
branch-line terminated in the Rubialian Stock. The existing 
representatives of this stock are the tropical Rubiaceae and the 
temperate Caprifoliaceae (Rubiales), closely allied families differing 
chiefly in vegetative characters—possibly the result of the great and 
long-standing difference in habitat. In Caprifoliaceae, moreover, 
appear the beginnings of those tendencies which led to the sole 
progeny of the rubialian group, Dipsacales ; namely, the tendency 
to Individual Zygomorphy coupled, as is usual, with oligomery in 
the andrcecium, and the tendency to reduction of the ovary to a, 
single fertile loculus. In Dipsacaceae, determined by a special 
tendency to aggregation, we may find both types of zygomorphy 
illustrated in the same inflorescence, and even in the same 
flower; and the aggregation is accompanied, as in Compositae, 
Brunoniaceae, and other families characterized by heads of flowers, 
by reduction of the ovary to a single chamber occupied by a 
single ovule. 
The final conclusion of our investigations is that the Sympetalae 
are polyphyletic, in the sense that their origin cannot be traced to 
a single sympetalous ancestry. We have found, on the contrary, 
that the sympetalous Dicotyledons have descended from Archi- 
chlamydeae along seven distinct lines, viz :— 
1. Centrospermae-PRiMULALES. 
2. Geraniales-ERiCALES. 
3. Guttiferales-EBENALES. 
4. Geraniales [Plantaginales] . Contort.e-Tubiflor>e. 
5. Calyciflorae-Umbelliflorae-RuBiALES-DiPSACALES (Aggre¬ 
gate). 
6. Calyciflorae-CAMPANULAT^:. 
7. Calyciflorae-Passiflorales-CucuRBiTALES. 
We have adopted the names of actual groups—some borrowed 
from Bentham and Hooker as being more explicit; but the lines are 
to be conceived as traceable through hypothetical stocks rather 
than through existing groups. 
