﻿238 RELATIONSHIPS. 



ancestor of the existing and Mesozoic cycads, as a plant with a Lyginodendron- 

 like trunk, bearing micro- and megasporophylls on the main axis monceciously 

 with cycad-like pollen and seeds already developed. 



Now, if the Cycadeoidete and Cycadea; thus arose from such a closed and 

 homogeneous evolutionary series, and then began to separate more and more widely 

 quite as early as the Permian, they must be regarded as fundamentally related. 

 And that they did so arise, and are so related, and that this second hypothesis, in 

 strictest accord with purely morphological data, thus expresses the approximate 

 truth, is our belief, after patient consideration of the botanical and paleontological 

 evidence. In short, the explanatory analogies offered by the reproductive features 

 of the two groups, when considered in connectiou with vegetative similarity, 

 inhibits derivation from other than a closed group. This being the simpler view, 

 and paleontologic evidence affording nothing in favor of a complex homoplastic 

 derivation, we are forced to the conclusion that the Cycadeoidete, as an ancient 

 apposite of the Cycadeee, find their appropriate place amongst the true Cycadales. 

 Were we in ignorance of the quite as ancient Cycas with its huge terminal strobilus 

 of carpellary leaves and its stamiuate cones, no one would hesitate to assign the 

 Cycadeoidete to the position of a separate great group. To do so, however, is to 

 neglect the simpler hypotheses of descent, the similarity of vegetative characters, and 

 the profoundly significant inverse relationship between the staminate fronds of 

 Cycadeoidea and the carpellary leaves of Cycas. 



