76 



MORPHOLOGY OF GYMNOSPERMS 



spreading of these remarkable stamens during the shedding of pollen 

 (fig. 60). The strobili of Williamsonia gigas, regarded by William- 

 son as "male flowers," have been reinvestigated by Lignier (18), 

 who has discovered them to contain a stout pyriform axis from which 

 the seeds had probably become detached after maturity, and also 



Fig. 60. — Cycadeoidea dacotensis: semi-diagrammatic sketch of strobilus; the 

 ovulate cone in the center is covered by short-stalked ovules and interseminal scales; 

 one staminate sporophyll expanded, and one still folded; outside the staminate sporo- 

 phvUs are hairy bracts; a httle less than natural size. — After Wieland (22). 



traces of the stamen set. Recently Nathorst (31) has found addi- 

 tional "male flowers" of Williamsofiia on the Yorkshire coast, and 

 confirms the view that they are bisporangiate strobili of the cyca- 

 deoidean type. About the same time Wieland (30) discovered 

 a well-preserved staminate disk of Williamsonia in the ISIexican 

 deposits, which he describes as being a "reduced campanulate form," 

 comprising eight to ten small and strictly once-pinnate sporophylls. 



