EVOLUTION OF SEED-PLANTS 101 



for it is the evolution of the whole body of Seed- 

 bearing Plants which is in question. 



We must now turn to the Flora of the Palaeo- 

 zoic period, by which, for our present purpose, 

 we mean the Permian, Carboniferous and Devo- 

 nian strata (see Table, p. 22), for we know little 

 as yet of the plants of the still older rocks. 



Just as the Mesozoic period has been called 

 "the Age of Gymnosperms" so has the Palaeo- 

 zoic long been known as "the Age of Crypto- 

 gams." Certainly it is true that Spore-plants 

 then formed a vastly more important element 

 in the Flora than at any subsequent time; it 

 is even probable that they were the main con- 

 stituent of the great swampy forests which gave 

 rise to the coal. Recent work, however, has 

 shorn the Palaeozoic world of Cryptogams of 

 some of its glories. 



The Flora of the Carboniferous epoch (by far 

 the best known Palaeozoic Flora) was, on a super- 

 ficial view, made up of five great groups of the 

 higher plants: 



The Cordaiteae, Gymnospermous trees; 



The Horsetail family, which were also trees in 

 those days; 



The Sphenophylls, a group now extinct, dis- 

 tantly related to the preceding (see Chapter 

 VII); 



