Origin and Development of the Composita. 221 
Chapter XIV. 
THE STORY OF THE COMPOSITE IN TIME AND SPACE. 
T HE conclusions arrived at in the preceding section are sum¬ 
marised in Fig. 79. The geographical centre of origin of 
each tribe is indicated by a number corresponding to the table of 
regions on the left. The primitive genera are indicated in those 
cases where they are obvious without any detailed discussion of all 
the genera in the group. In some cases the centre of origin as given 
in Fig. 79 does not coincide with the main centre of concentration 
as given in Chap. X; this is because the probable primitive genus 
has its centre of origin in a region different from that of the chief 
development of the genera of the group. The change is made at 
this stage so that Fig. 79 may form the basis of future discussions 
and for that reason it should be as nearly a true representation of 
the history of the family as it is possible to attain without a detailed 
consideration of each one of the 23,000 species. The time of 
the origin of each sub-tribe, as deduced from the palaeobotanical 
evidence and from the present development, generic and specific 
differentiation and area of the various groups, is also indicated. 
An attempt will now be made, using Fig. 79 as a basis, to give 
that “ coherent account of the evolution of the family ” which, as 
mentioned in the Introduction, can be attained by the use of “the 
modern theories of heredity, evolution and geographical distribu¬ 
tion.” The writer’s problem is to convey to the mind of the reader 
something of the activity and individuality which have been shown in 
the development of this immense family. A similar attempt was 
made in Chap. XI to picture the evolution of Seuecio, but the cross- 
references given there interrupt the flow of the narrative and, in 
the present case, the reader is referred to all that precedes this last 
chapter for the proofs, the evidence for suggestions and the discus¬ 
sion of the various problems raised. 
In the days immediately preceding the Cretaceous uplift on the 
west coast of South America, the Angiosperms had developed a 
multitude of forms which represented most of the larger families now 
existing. The forests of the Amazons to this day retain the very 
mixed character of this nursery of the Angiosperms: no one group 
was or is dominant, while the vegetative characters varied 
comparatively slightly owing to the similarity of conditions through¬ 
out a wide expanse of country. The inherent instability of this 
comparatively new plexus was the cause of the many mutations 
