ii4 ANCIENT PLANTS 



CHAPTER XII 



PAST HISTORIES OF PLANT FAMILIES 

 V. Pteridosperms 



This group consists entirely of plants which are ex- 

 tinct, and which were in the height of their development 

 in the Coal Measure period. As a group they are the 

 most recently discovered in the plant world, and but a 

 few years ago the name " Pteridosperm " was unknown. 

 They form, however, both one of the most interesting 

 of plant families and one of the most numerous of those 

 which flourished inr the Carboniferous period. 



To mention first the vital point of interest in their 

 structure, they show leaves which in all respects appear 

 like ordinary foliage leaves, and yet bear seeds. These 

 -leaves, which we now know bore the seeds, had long 

 been considered as typical fern leaves, and had been 

 named and described as fern leaves. There are two 

 extremely important results from the discovery of this 

 fossil group, viz. that leaves, to all appearance like 

 ordinary foliage, can directly bear seeds, and that the 

 leaves, though like fern leaves, bore seeds like those 

 of a Cycad. 



As the name Pteridosperm indicates, the group is a 

 link between the ferns and the seed-bearing plants, and 

 as such is of special interest and value to botanists. 



The gradual recognition of this group from among 

 the numerous plant fragments of Palaeozoic age is one 

 of the most interesting of the accumulative discoveries 

 of fossil botany. Ever since fossil remains attracted the 

 attention of enquiring minds many " ferns " have been 

 recognized among the rich impressions of the Coal 

 Measures. Most of them, however, were not connected 

 with any structural material, and were given many dif- 

 ferent names of specific value. So numerous were these 

 fern "species" that it was supposed that in the Coal 



