PTERlDOtfHYTES 



101 



produced descendants, and among these descendants are the 

 Pteridophytes of the present time. The history and fate 

 of these ancient groups may be likened to the history and 

 fate of such old empires 

 as those of Egypt, Greece, 

 and Rome, which lived 

 and flourished and then 

 disappeared, but they 

 also gave rise to descend- 

 ants, and among these 

 descendants are various 

 nations of the present 

 time. 



There are three promi- 

 nent groups of Pterido- 

 phytes living to-day, and 

 they are common enough 

 to deserve recognition. 



(1) Club-mosses (Ly- 

 copodiales) . These 

 plants, resembling coarse 

 mosses, are recognized 

 by their numerous small 

 leaves (Figs. 71 and 75), 

 and by the fact that the 

 sporangium-bearing 

 leaves (sporophylls) bear 

 a single sporangium upon 

 the upper surface near 

 the base. They are 

 sometimes called 

 "ground pines," because 

 the coarser ones resemble seedling pines in general appear- 

 ance. Among the ancestors of the present Lycopodiales 

 there were large trees, so that during the Coal Age the 

 8 



FIG. 82. A branching Equisetum. 



