68 



occur in the nieghboring family, the Elatinaceae, and also in 

 Cistaceae and several other families usually included in the 

 order Parietales. However, in some of the genera apparently 

 nearest to Frankenia, such as Dianthus and Velezia, the embryo 

 is nearly straight (fig. 12). In sectioning a few seeds of a North 

 African Frankenia, the embryo seems to be situated not quite 

 in the center of the endosperm. 



If the Frankeniaceae and the Caryophyllaceae belong to- 

 gether, the orders which contain them, in so far as they are 

 natural, must also belong together. Considering only widely 

 occurring characters in the two groups Parietales and Centro- 

 spermae, those of the former appear to be the more primitive; 

 those of the latter the more specialized. 



Parietales Centrospermae 



Largely woody plants Nearly all herbaceous 



Floral parts sometimes spirally Spiral arrangement rare 



arranged (Chenopodiaceae) 



Stamens often numerous Stamens usually in two whorls 



Placentation axile or parietal Placentation central or basal 



or basal 



Embryo straight or slightly Embryo usually much curved 



curved 



The comparatively late position in the Engler system of the 

 order Parietales must be considered as due to the requirements 

 of a linear sequence, for through Dilleniaceae and other families 

 this group connects directly with the Magnolia group. 



The great changes in classification which would follow from a 

 recognition of a relationship of Frankeniaceae and Caryo- 

 phyllaceae make it desirable to examine more closely the prob- 

 able lines of evolution within these families. 



Brooklyn Botanic Garden, 

 Brooklyn, N. Y. 



