192 THE EVOLUTION OF PLANTS 



The main family of Lycopods in Palaeozoic 

 times, the Lepidodendreae, were heterosporous 

 trees, quite distinct from, though related to the 

 contemporary Selaginella type. They were a 

 dominant race in their day, when some among 

 them adopted the seed-method of reproduction; 

 they appear to have left few, if any, descendants, 

 Isoetes being the only living genus which may 

 possibly represent the family in a state of extreme 

 reduction. 



We have no light of any kind on the origin of 

 the Lycopods they are too ancient for that to 

 be possible, unless the record should be traced 

 much further back than has yet been done. 

 So far as we can follow them, they have always 

 been distinct from any other race of plants, 

 and while varying immensely in stature and 

 elaboration, have always maintained the same 

 general characters, especially as regards the 

 nature of the leaf, and the relation between 

 sporangium and sporophyll. 



The Lycopods are an isolated class of plants 

 in the existing Flora, and the extensive records 

 of their past history which we possess do not at 

 present tend to remove them from their isolation. 



