PAST HISTORIES OF PLANT FAMILIES 159 



[Ckeirostrobus) is, however, so complex that it would 

 take far too much space to describe it in detail. Even 

 a diagram of its arrangements is extraordinarily ela- 

 borate. To the specialist the cone is peculiarly fas- 

 cinating, for its very complexity gives him great scope 

 for weaving theories about it; but for our purposes most 

 of these are too abstruse. 



Its most important features are the following. Round 



Fig. 118. — A, Diagram of Three-lobed Bract from Cone of Ckeirostrobus. li, Axis; 

 Ir, the three sterile lower lobes of the bract ; sp, the three upper sporophyll-like lobes, 

 to each of which were attached four sporangia s. B, Part of the above seen in section 

 longitudinal to the axis. (Modified from .Scott. ) 



the axis were series of scales, twelve in each whorl, and 

 each scale was divided into an upper and a lower por- 

 tion, each of which again divided into three lobes. The 

 lower three of each of these scale groups were sterile 

 and bractlike, comparable, perhaps, with the bracts in 

 fig. 116; while the upper three divisions were stalks 

 round each of which were four sporangia. Each sporo- 

 phyll segment thus resembled the sporophyll of Cala- 



mites, while the 



long 



sausage 



-shaped sporangia them- 



