THE EVOLUTION OF PLANTS 



577 



ANCCSTRAI BRvoPHVTA(/Vy POTHETICAL.) 



FIG. 410. Hypothetical genealogical tree to illustrate the probable affini- 

 ties of the modern plant orders. This diagram is intended to indicate that 

 the plant orders now existing are the tips, only, of the branches of a genealog- 

 ical tree, whose lower limbs and roots extend into preceding geological 

 periods. Our knowledge is not sufficient to enable us to connect these 

 branches with each other, nor with the main trunk. The diagram teaches 

 that hypothetical (indicated by the dotted line) Anthocerotales gave rise 

 to a now fossil Filicalean stock, from which have been derived all the 

 modern orders above the mosses and liverworts. 



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