378 



STRUCTURE AND LIFE HISTORIES 



leaves, but no sporophylls, while the fertile region occurs 

 as a clearly recognized cone, formed by the crowding of 

 the sporophylls at the apex of the leafy axis (Fig. 273). 

 The foliage-leaves are all simple and small (microphyllous) . 



Fig. 273. — Lycopodium Sp. Photomicrograph of longitudinal section 

 of a cone, showing the sporangia on the upper surface of the sporophylls, 

 near their insertion on the main axis. 



A more primitive type is found in Lycopodium Selago 

 (Fig. 274). Here the lower region is sterile, but is not 

 as well developed as in other types, for the sporophylls 

 begin to appear lower down on the stem. Moreover the 

 sporophylls are not aggregated into a cone, but are dis- 

 tributed at intervals from near the base to near the apex, 



