THE EVOLUTION OF PLANTS 



619 



nothing but one particular stage in the evolution of the 

 Vegetable Kingdom."^ 



Table VIII 



Ascendancy 



Periods 



Persistence and relationship of 

 great groups 



VII. Reign of Angiosperms 



Tertiary 



Cretaceous 



Comanchian 



VI. Reign of Pro-angiosperms 



Jurassic 

 Triassic 

 Permian 



V. Reign of Acrogens (High- Pennsylvanian 

 er Equisetes. Lycopods,! Mississippian 

 etc.) i 



IV. Reign of Gymnospertns | Devonian 



III. Reign of Early Land 

 Plants 



Silurian 



Ordovician 



S- Actual Fossil Land Plant rec- 

 ord begins 

 4. Primofilices — Early Equisetes 

 3. Basal Plant Complex with va- 

 riety of species 



II. Reign of Algae 



Cambrian 

 Precambrian 

 (Proterozoic) 



Differentiation of Dry 



and Aquatic Plants 

 (Fossil Algae abundant) 



Land 



Reign -of Primitive Life 

 (Hypothetical) 



Old P r e c a m- 



brian 

 (Archeozoic) 



(Fossil Algae begin) 

 I. Primitive Protoplasm 

 Unicellular Life 



and 



In the above table (after Wieland), the groups are to be considered as 

 arranged on an unrolled cylinder, projected from a hemisphere; thus the 

 phyletic lines are to be pictured as diverging upward and the Cordaitales 

 as coming between the Ginkgoales and Filicales, to both of which the}^ 

 are related. 



629. The Element of Geological Time. — How many 

 years has it taken for the evolution of the higher Angio- 

 sperms — that is, from the dawn of the fossil record in the 



* Scott, D. H. "Studies in Fossil Botany," p. 3. 



