34 



GYMNOSPERMS 



producing, in two great groups of plants, leaves so identical that they 

 cannot be distinguished. 



Fig. 26. — Bothrodendron. A, microsporangium, showing portion of sporophyll, 

 course of vascular strand, ligulc, and tetrads of spores; X 10. B, tetrad of microspores; 

 X230. C, diagram of megasporangium showing sporophyll with lobe or projection of 

 lower side, and one of the four megaspores; X9. D, diagram of megasporangium show- 

 ing two megaspores; X9. E, diagram of megasporangium: /, ligule; />, lobe on sporo- 

 phyll; X9. F, megasporangium with three of the four megaspores: v, vascular strand; 

 /, ligule; /, tapctal plasmodium; g, female gametophyte; somewhat diagrammatic; X 16. 

 — After Dr. Fredda D. Reed.-''" 



We believe that the evidence is sufllcient to prove, as well as any- 

 thing is proved in the way of genetic relationships, that the Cyca- 

 dofilicales have come, in the natural course of evolution, from the 



