Origin and Development of the Composite. 218 
American Gochnatiinae and the A inslitza-Dicoma group as the source 
of the Old World Gochnatiinae. As Ainslicea is more closely allied 
to Mutisia than Dicoma , that genus may be substituted for the 
double group. 
Gerbera and Chaptalia, which are separated only by the 
abortion of the posterior lip of the ray florets in the latter and its 
presence in the former genus and by their geographical localities, 
form a very good basal plexus for the Gerberinae. The differences 
between these two genera and Onoseris are of no more than specific 
rank in other genera, except for the type XII style of Gerbera and 
Chaptalia and the type IX style of Onoseris. A glance at Fig. 5 will 
show that the type IX style could be regarded as a type XIla style 
in which the stigmatic papillae had spread over the whole of the 
inner surface and in which the style branches had closed up. The 
former style would be the more primitive, but the difference is so 
slight that the evolution of the Gerberinae from Onoseris is quite 
probable. These suggestions involve a slight change in Fig. 7 
which would bring off the Gochnatiinae from the Onoseridinae 
instead of from the Gerberinae. 
The two genera of the Barnadesiinae, Barnadesia and 
Schlechteudahlia with type 3 or type 4 stamens and type IX styles 
have probably arisen separately from distinct sources, and this 
sub-tribe is another example of polyphyly and convergent 
evolution. Until a detailed examination of their affinities has been 
made they can be regarded as a separate development, as shown in 
Fig. 7. 
The separation of the Mutisieae into two geographical groups 
furnishes some clue to the early history of the tribe. That the 
separation is geologically recent is proved by the affinity of 
Gerbera and Chaptalia. That the separation was due to the last 
Glacial Epoch is rendered probable by the recency of the event 
and by the fact that the Mutisieae are tropical and subtropical 
plants. Such species, although they probably crossed the Alaska- 
Siberian bridge during the pre-glacial and interglacial warm 
periods, were unable to survive in the more northern latitudes 
during the period of glaciation and only a few primitive, i.e., 
physiologically undifferentiated, species, such as Gerbera Anan - 
dria, are even now becoming acclimatised to sub-arctic conditions. 
The origin of Trixis is thus thrown back some considerable 
time to allow for the differentiation and dispersal of the higher 
types, such as Gerbera. Since the area occupied by the tribe is 
