THE STORY TOLD BY FOSSIL PLANTS 



The long procession of changing forms has not yet come 

 to a halt, and man, having learned some of Nature's 

 methods, has so applied them as to produce marvellous new 

 varieties of flower and fruit, new habits of growth, and new 

 adaptability to environment. 



We have seen in our brief survey of the floras of the past 

 that they illustrate the evolutionary principles set forth. We 

 observe a gradual transformation from simple and general- 

 ized to complex and specialized forms. We see different 

 groups becoming specialized in various ways and attaining 

 dominance for a time, and eventually we see those that were 

 less perfectly adapted to survive going down in competition 

 with those that were more perfectly adapted. At one time 

 it may be the Palaeozoic club mosses, whose trunks were 

 mechanically defective as compared with the trunks of the 

 contemporary exogenous conifers. At another time we see 

 the seed ferns, with their large and complex seeds, replaced 

 by plants having simpler and more efficient seeds. In one 

 way or another the story repeats itself through millions of 

 years of history. 



REFERENCES 



Berry, Edward W. Paleobotany: A Sketch of the Origin and Evo- 

 lution of Floras. Smithsonian Institution, Ann. Rept. for 

 1918, pp. 289-407, 1920. 



Berry, Edward Wilder. Tree Ancestors. A Glimpse Into the 

 Past. Williams & Wilklns Co., Baltimore, 1923. 



Knowlton, Frank Hall. Plants of the Past. Princeton Uni- 

 versity Press, 1927. 



Scott, Dunkinfield Henry. Studies in Fossil Botany. 3rd ed., 2 

 vols. A. & C. Black, London, 1920-1923. Extinct Plants and 

 Problems of Evolution. Macmillan & Co., London, 1924. 



Seward, A. C. Fossil Plants. 4 volumes. Cambridge University 

 Press, 1898-1919. 



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