CHAPTER I 



INTRODUCTION 



The gymnosperm line is one of extreme age, reaching back at least 

 two or three hundred millions of years — so far back that its origin is 

 lost in that distant past. But when we get our first glimpse of the 

 group there were already two distinct lines, the Cycadophytes and 

 the Coniferophytes, differing from each other in easily distinguish- 

 able characters. Whether these two lines, millions of years back of 

 any records yet discovered, may have had a common origin, we do 

 not know. We simply know that the earliest material which has 

 been found and studied shows the two lines about as sharply sepa- 

 rated as their living representatives are today. 



That the gymnosperms did not originate as seed plants we believe 

 to be self-evident. The old Greeks believed that Minerva, dressed in 

 full armor, sprang from the head of Jove; but such an explanation of 

 the origin of a group of plants would hardly satisfy a modern biolo- 

 gist. For the more immediate origin of the gymnosperms we look to 

 the Pteridophytes, for we believe that they were the ancestors of the 

 gymnosperms. 



Of course, all the material for a study of the early gymnosperms 

 is fossil, a record left in stone. By far the greater part of this record 

 consists of impressions, and most of the impressions are those of 

 leaves and stems, with some roots; but there are some impressions 

 of reproductive structures. A leaf would fall into the sand or clay; 

 then the sand or clay would become solid stone; all organic parts 

 would be dissolved, and only the form would remain. 



Some material behaved differently. The most valuable material is 

 in the form of calcareous nodules, called "coal balls," which are 

 found scattered through coal seams like raisins in a cake. Coal balls 

 were probably produced when water, with calcium or silica in solu- 

 tion, invaded a swamp which formed a coal bed. The solution satu- 

 rated plant tissues and preserved them, just as fixing solutions do 

 today. Then the material solidified so that the plants were imbedded 



