100 EVOLUTION OF PLANTS 



the groups now exist, the three classes, Ascomycetes, 

 JEcidiomycetes, and Basidiomycetes, have very little 

 in common, although it is probable that the two latter 

 have had a common origin. 



The Lichens must be supposed to have had a multiple 

 origin, like the Phycomycetes. The majority have been 

 derived from different groups of ascomycetous fungi, 

 but some of them are allied to the Basidiomycetes. 



We may then consider the Fungi as an aberrant 

 group of plants, probably but not certainly derived 

 from originally green ancestors, but which have di- 

 verged so widely from the parent stock that they have 

 lost nearly all of their original characteristics. 



