128 



ANCIENT PLANTS 



the Pteridosperms, cf. fig. 8i and fig. 90. These are 

 unlike the characteristic wood cells of modern ferns and 

 of the other family of Palaeozoic ferns. 



The foliage of most members of the family is un- 

 known, or at least, of the many impressions which 

 possibly belong to the different genera, the most part 

 have not yet been connected with their corresponding 



structural material. There are 

 indications, however, that the 

 leaves were large and complexly 

 divided. 



The fructifications were pre- 

 sumably fern sporangia of nor- 

 mal but rather massive type. 

 Of most genera they are not 

 known, though in a few they 

 have been found in connection 

 with recognizable parts of their 

 tissue. The best known of the 

 sporangia are large, in com- 

 parison with living sporangia 

 (actually about 2.5 millimetres 

 long), oval sacs clustered to- 

 gether on little pedicels. The 

 spores within them seem in no 

 way essentially different from 

 normal fern spores. 



The coexistence of the Bot- 

 ryopteridese and Pteridosperms, and the several points 

 in the structure of the former which seem to lead up 

 to the characters of the latter group, are significant. 

 The Botryopterideae, even were they an entirely isolated 

 group, would be interesting from the variety of struc- 

 tures and the variations of the monostele in their 

 anatomy; and the prominent place they held in the 

 Palaeozoic flora, as the greatest family of ferns of that 

 period, gives them an important position in fossil botany. 

 The other family of importance in Palaeozoic times, 



Fig. 90. — Tracheas of Wood of 

 Botryopteridean Fern in Longitu- 

 dinal Section, showing the rows of 

 pits on the walls. (Microphoto.) 



