130 Plant Life and Evolution 



as, for example, the extensively spreading root- 

 stocks of the horsetails or the bracken fern, and 

 in some of the club-mosses; or where there is a 

 constant supply of moisture, as in many tropical 

 mountain regions or countries like New Zealand. 

 In such favored regions ferns may often constitute 

 an important factor of the flora and hold their 

 own very successfully with the seed-plants. 



The First Seed-plants. The lower types of seed- 

 plants are mostly trees or shrubs whose resistant 

 tissues have in many cases been preserved in a fossil 

 state in an astonishingly perfect manner, and con- 

 sequently the geological record is especially satis- 

 factory in regard to these important forms. A study 

 of these fossils shows that the seed habit arose at 

 a very early period. The earliest seed-bearing plants 

 were very different from any living types, and they 

 have been separated as a separate order, known as 

 the Cordaitales. The affinities of the latter with 

 other plants are extremely doubtful, and it is a 

 question whether they are related at all to any ex- 

 isting species. The Cordaitales are found as far 

 back as the Devonian, and possibly even earlier, and 

 were especially abundant during the Carboniferous. 

 They became quite extinct before the end of the 

 Paleozoic. 



Origin of Seed-plants. The fern-like plants, 

 which are first certainly evident in the Devonian, 

 where many forms flourished, like all of the types 

 of pteridophytes had an extraordinary develop- 



