THE EVOLUTION OF PLANTS 



2I 7 



Hemicycadales possess many of the primitive anatomical 

 features that characterize the Cycadofilicales, their 

 development of a bisporangiate strobilus with two sets 

 of sporophylls, related to one another, as they are in the 

 flower of the Angiosperms, indicates a genetic relationship 

 to that group, as does also the fact that the seeds, enclosed 

 in a fruit, possess a dicotyledonous embryo, without endo- 



FIG. 101. Flower of magnolia. (Cf. Fig. 102.) 



sperm. In other features the Hemicycadales are unlike 

 the Angiosperms; the ovules, for example, are enclosed 

 by sterile scales, instead of by the carpels on which they 

 are borne, and the protrusion of the pollen-chamber 

 through the micropyle signifies the gymnospermous type of 

 fertilization. 



These and other comparisons indicate that the Hemi- 

 cycadales were essentially Gymnosperms having certain 



