304 Camp emulates. 
close inflorescence and from a common receptacle. Dipsacaceae 
and Valeriancete, in obedience to the tendencies of their ancestral 
stock, are exceptional in exhibiting zygomorphy in the individual 
florets; but it must be remembered that, compared with Composite 
and Umbelliferae, these two families are exceedingly small in point 
of number of species ; so that we may conclude finally that the most 
successful tendencies of descent have been those which produced 
a densely-aggregated inflorescence, together with the concomitant 
and, as we have endeavoured to explain, consequent characters of 
zygomorphy, epigyny, and the solitary megasporangium, maturing 
into a seed dispersed typically by the aid of a modified calyx. 
It is in the classification of the Inferae that the system of 
Engler differs most fundamentally from that of Bentham and 
Hooker in respect of the Sympetalae, and some comment upon this 
difference may not be out of place. 
The difference concerns the union of the families into groups 
of higher order ; the families themselves are virtually identical in 
both systems. Bentham and Hooker, in associating Valerianaceae 
and Dipsacaceas with Compositae and Calyceraceae (Asterales), and 
in separating the group so formed from Campanulaceae and their 
allies (Campanales), have emphasized the uniovulate character of 
the ovary to the exclusion of all other considerations. But our 
examination of the ancestry and affinities of the Inferae has led us 
to associate Compositse with Campanulaceae, and to separate them 
from Dipsacales ; and we have endeavoured to trace the connection 
between the last-named group and Rubiales. General biological 
tendencies have been our guide throughout; and this would seem 
to be the proper course in the discussion of the larger plant- 
groups. Seeing that the most advanced plant-forms are concerned, 
it is to be expected that the dominating tendencies should be those 
associated with adaptation for insect-visitors rather than merely 
with economy of reproductive parts; and in the light of such 
tendencies we have been led to the sharp separation of a Campanal 
or pollen-presentation series from a Rubialian or umbellifloral 
series. In both series we have met with aggregation of florets 
and with reduction in ovule-number; hence the similarity between 
Composite and Dipsacaceae—a similarity which does not, however, 
justify the conclusion that these two families have been derived 
from the same proximate ancestral stock,— i,e., that they should 
be associated in the same cohort. 
