360 



BOTANICAL GAZETTE 



[NOVEMBER 



of elongated cells similar to those of the younger condition of the 

 strobilus. Occasionally the xylem extends a short distance into the 

 stalk of the sporophyll, the bundle here, however, usually consisting 





Figs. 13-22. — Cross-sections of mature strobilus at approximately levels indicated 

 by numbers to left of strobilus shown in fig. 9; branches of bundles to various sporo- 

 phylls indicated by a, b, c, etc., xylem indicated by black; bundles a and b supply 

 terminal sporophylls; union of bundles indicated by combining letters, a,s jd in figs. 

 17-19; fig. 19 shows complete cylinder below lowermost sporophyll; in fig. 18 / and c 

 united, in fig. 19 separated, in fig. 20 c and m united, and in fig. 22 km one of the 3 

 large strands from sterile portion of axis; fig. 22 also shows traces to 3 uppermost 

 scales, SCI, sc2, and scj; note concentric character of terminal portions, as in c, d, and 

 e, in fig. is; X36. 



only of the phloem portion (fig. 39), the xylem usually ending within 

 the cortex of the axis. 



The bundles of this region are collateral endarch in the lower 

 portions. In the upper portions, however, the bundles frequently 

 show centripetal xylem (figs. 40, 44), giving mesarch bundles, and 



