SPERMATOPHYTA 



63 



It has seemed evident to students of these analogies that the 

 cycadeoids, as their name implies, are closely related to the cycads, 

 and that both groups sprang separately from certain Paleozoic 

 fernS; the marattiaceous type. Moreover, the structure of their 



Fig. 21 a. — The unexpanded flower of Cycadeoidea dacotensis Macbride, from the 

 terrestrial deposits of Upper Jurassic age in South Dakota. Photograph ( X 2) 

 of a vertical section of a silicified specimen. The lines refer to various sections 

 through the flower pubHshed in Wieland's "Am. Fos. Cycads." p., pinnules: 

 r., receptacle. 



fructification, the arrangement of its parts into a '' flower," 

 suggests that the cycadeoids represent an intermediate stage 

 in the supposed line of development of the angiosperms from 

 their fern ancestors. 



