PAST HISTORIES OF PLANT FAMILIES 



141 



Fig. 99. — Transverse Section througlj Cone of Lepidodendron 



A, Main axis with woody tissue; st, stalks of sporophylls cut in oblique longi- 

 tudinal direction ; s, tips of sporophylls cut across ; s, sporangia with a few 

 groups of spores. (Microphoto.) 



The section shown in fig. 100 

 angles to that in which the spo- 

 rangia are shown in fig. 98, viz. 

 tangfential to the axis. A remark- 

 able feature of the plant is that 

 there were also round those spo- 

 rangia which bore the numerous 

 small spores (corresponding to 

 pollen grains) enclosing integu- 

 ment-like flaps similar to those 

 shown in fig. 100, sp. f. 



This type of fructification is 

 the nearest approach to seed and 

 pollen grains reached by any of 

 the Pteridophytes, and its appear- 

 ance at a time when the Lycopods 

 were one of the dominant families 



is that cut at risfht 



Fig. 100. — Section through one 

 Sporangium of Lepidocarpon 



sp, Sporophyll; sp.f., flaps of 

 sporophyll protecting sporan- 

 gium ; s, large spore within the 

 sporangium wall w ; s, the three 

 aborted spores of the tetrad to 

 which s belongs. 



