230 THE EVOLUTION OF PLANTS 



Plants to Insect life and in other ways show 

 progress in many directions, corresponding to in- 

 creased complexity in the conditions of life. It 

 must be borne in mind, however, that we know 

 very little as yet about such special adaptations 

 among plants of earlier periods 



A very curious point in the geological history 

 of plants is the uniform character of the Flora 

 all over the world during long periods. Professor 

 Seward has recently said: "In dealing with the 

 relation of the Yorkshire Jurassic Flora with that 

 of other parts of the world, it is remarkable to find 

 that almost precisely similar plants to those occur- 

 ring in the local rocks also are found embedded in 

 strata of about the same age at places so far 

 distant as Bornholm, Poland, Turkestan, Siberia, 

 Korea, Japan, Franz Josef Land, Spitzbergen, 

 Greenland, America, India and Australia." 



A similar statement would hold good for the 

 earlier Palaeozoic Floras, though at the close of 

 this period there was more distinction in the 

 vegetation, at any rate of the Northern and 

 Southern hemispheres. 



The uniform Flora of the world at the periods 

 mentioned is usually regarded as a proof of com- 

 parative uniformity of climate. It is possible, 

 however, that the explanation may lie in the 

 greater adaptability of the plants themselves. 

 Certain plants at the present day make them- 



