/// 



112 



Fig. Ill . — Dioon edule: longitudinal section of microsporangium, showing numerous 

 microspores and typical structure of a eusporangiate sporangium. Two ramental hairs, 

 each with one transverse wall, are shown on the lower left part of the sporangium. — 

 From Chamberlain, The Living Cycads"° (University of Chicago Press). 



Fig. 112. — Angiopteris eveda: a typical eusporangiate sporangium, much like that 

 of the carboniferous Cycadofilicales. — From Chamberlain, The Living Cycads"" (Uni- 

 versity of Chicago Press). 



Fig. 113. — Stangeria paradoxa: section of part of microsporangium with micro- 

 spores. The cell walls of the outer layer are becoming very thick; the tapetal cells have 

 broken down into a tapetal Plasmodium. Finally, all the cells between the spores and 

 the outer layer will be absorbed by the growing microspores. 



