PTERIDOPHYTA 



257 



Fig. 214. Portion of restoration of Carboniferous swamp lorest m the Chicago Natural 

 History Museum, showing Calamites (tree in center) and a fallen trunk of Sigillaria. The 

 small plants in the foreground are Sphenophyllum emarginatum. 



each node. Branches, where present, are also whorled and arise alter- 

 nately with the leaves. The vascular system of the stem is a much- 

 reduced ectophloic siphonostele with widely separated, endarch, collateral 

 bundles. There is no secondary thickening. All species are homospo- 

 rous and have a definite strobilus composed of whorled, peltate sporangio- 

 phores, each bearing 5 to 10 pendent sporangia with longitudinal dehis- 



