XI] STROBILUS. 403 



of a widely open funnel-shaped disc, which splits up peripherally 

 into 14 — 20 linear-lanceolate segments. The free segments of 

 each verticil have an obliquely ascending or almost vertical posi- 

 tion, and extend upwards for a distance of about six intemodes. 

 The smaller drawing in fig. 108 shows the appearance in side 

 view of the narrow bracts of a single whorl. A transverse 

 section of a strobilus would include, therefore, sections of 

 several concentric series of ascending bracts. The verticils of 

 Sphenophyllostachys Dawsoni are probably superposed, but this 

 point has not been definitely settled. From the upper surface 

 of the coherent basal portion of each verticil, there are given off 

 twice as many sporangiophores as there are free segments, and 

 these are attached close to the line of junction of the axis of the 

 cone and the funnel-shaped disc. Each sporangiophore has the 

 form of a slender stalk which bends inwards at its distal end 

 and bears a single sporangium (c/. fig. 107, D). The sporangio- 

 phores given off from the same verticil of bracts vary in length. 

 All the sporangiophores are attached to the coherent bracts at 

 the same distance from the axis of the cone ; but ag the sporangia 

 between each verticil of bracts are arranged in two or three 

 concentric series, it follows that the length of the sporangio- 

 phores varies considerably. The diagrammatic longitudinal 

 section of a strobilus in fig. 108 shows three concentric series 

 of sporangia between successive bract-verticils. A similar 

 diagram was published by Williamson in 1892 \ and after- 

 wards copied by Potonie'^, but in Williamson's restoration the 

 sporangiophores of the three series of sporangia are erroneously 

 represented as arising from different points on the surface of 

 the bracts. There is little doubt, as regards the strobilus of *S>. 

 cuneifolium, that the sporangiophores were given oflf in a single 

 series close to the axils of the bracts, as is partially shown in 

 fig. 108. 



The central part of the axis of the cone is occupied by a 

 single triangular stele like that of the stem, except that each 

 ray of the xylem strand has a comparatively broad blunt 

 termination, and is not tapered to a narrow arm as in fig. 105, 



1 Williamson (92). PoIui.m- y.i»,, lig. 1. 



26—2 



