Chapter 11 



NOTES ON THE MORPHOLOGY OF SELECTED FAMILIES 



The following discussion is restricted to the most important mor- 

 phological aspects of a few individual angiosperm families, chosen for 

 their importance in showing evolutionary modification in form and 

 probable phylogenetic relationships. 



The more primitive families, especially those of the Ranales and 

 Helobiales, have been studied intensively from 1920 to 1960, with atten- 

 tion to critical comparisons of all structure, both reproductive and 

 vegetative. These studies, based on the viewpoint that inferences as to 

 degree of primitiveness and closeness of relationship must be based on 

 the summation of all characters, have resulted in the suggestion of 

 many changes in the classification of the lower orders and families. 



In making the following selection of families, no attention has been 

 given to size of taxa or to possession of some unusual character. The 

 descriptions are not morphologically complete, nor are they uniform in 

 the various families, for only structure that illustrates change in form 

 discussed in the earlier chapters is emphasized. Added to the commonly 

 recognized primitive angiosperm taxa are a few families that present 

 especially puzzling structure, such as the Casuarinaceae. 



The sequence in treatment of the selected families is not intended 

 to suggest phylogenetic relationships, though families that seem to be 

 more or less closely related, as those of the magnolian plexus, are kept 

 together. Linear sequences are not evident in these taxa. The living 

 primitive families are obviously surviving remnants of an ancient stock 

 or stocks, and a phylogenetic "tree" cannot be looked for. It is more 

 and more clearly evident that there are several living stocks which have 

 much the same rank in number of primitive characters. 



RANALES 



WiNTERACEAE 



The Winteraceae are outstanding among angiosperm families, because 

 they show early stages in the history of many of the characteristic fea- 

 tures of angiosperm morphology. Together with the other families of 

 the Ranales, the Winteraceae provide a basis for many of the concepts 

 and theories of phylogenetic relationships among angiosperms. Among 



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