Sphenopsida 



Sporophyte with roots, stems and whorled leaves. 

 Protostelic (solid or medullated). Some with secon- 

 dary thickening. Sporangia thick-walled, homo- 

 sporous (or heterosporous), usually borne in a re- 

 flexed position on sporangiophores arranged in 

 whorls. Antherozoids multiflagellate. 



Hyeniales* 



Protohyeniaceae* Protohyenia* 

 Hyeniaceae* Hyenia* Calamophyton 



* 



2 Sphenophyllales* 



Sphenophyllaceae* Sphenophyllum* Sphenophyllos- 



tachys* Bowmanites,* Eviostachya* 

 Cheirostrobaceae* Cheirostrobus* 



3 Calamitales* 



Asterocalamitaceae* Asterocalamites* Archaeocala- 



mites* 



Calamitaceae* Protocalamites* Calamites,* 



Annularia,'^ Asterophyllites,* 

 Pro tocalamostachys, * Calamo- 

 stachys* Palaeostachya* 



4 Equisetales 



Equisetaceae Equisetites,* Equisetum 



94 



