EVOLUTIONARY PRINCIPLES OF THE COMPOSITAE 443 



group which forms the subject of the present chapter the only 

 data for regarding the Tubuliflorae and the Liguliflorae as respec- 



FIG. 306. Diagram of external habit and distribution of oil canals in the arti- 

 choke (C. Scolymus). 



tively lower and higher are morphological in their nature, the lines 

 of evidence in this connection are so numerous and so generally 

 admitted that there can be no reasonable doubt as to their validity. 



