GINKGOALES 



191 



THE MICROSPORANGIUM 



The staminate strobili consist of numerous microsporophylls 

 rising in loose catkin-like clusters from the axils of the scale leaves 

 developed at the summit of the dwarf shoot (figs. 216, 217). Com- 

 paring this strobilus with the staminate strobilus of Cordaitales, it 



216 217 



Figs. 216, 217. — Ginkgo biloba: fig. 216, branch with dwarf shoots bearing stami- 

 nate strobili and leaves; about natural size; fig. 217, single staminate strobilus, showing 

 character of individual stamens (a stalk ending in a knob and bearing two pendent 

 sporangia); X3.5. — After Coulter (54). 



is evident that if the intermixed sterile sporophylls and bracts of the 

 latter were ehminated, the general structure of the former would 

 be obtained. 



The strobili are first evident during the early summer of the year 

 preceding the maturing of the pollen (53), but are hidden in buds that 

 cannot be distinguished from leaf buds. The development of the 

 sporophylls is in acropetal succession, and the older sporangia reach 



