G. R. Wieland — Cycadeoidean Flower-hud Structure. 127 



of its close packing of bracts than to actually expand at the 

 time of maturity, unless indeed there was an immense later 

 growth as yet little suspected. 



Had both pollen and ovules reached maturity before the 

 splitting away of the disk, the arrangement would have facili- 

 tated close fertilization to an extraordinary degree, provided 



Figures 5-7. Cycadeoidea colossalis. Series of distinctly diagrammatic 

 restorations of fruit shown in the preceding drawings, given for the purpose 

 of further bringing to view the flower bud structure as it might appear were 

 such a flower freely expanded. 



In figure 5 a generalized sketch of the trial section is introduced to show 

 the ten V-shaped transverse sections of rachides as cut at base of the 

 terminal dome, the level of this section being indicated by the arrow 

 near summit of flower arbitrarily shown in expanded form with front 

 half cut away. Figs. 6 and 7 are merely repetitions of fig. 5. In all 

 three figures the seed zone and synangial region are represented much 

 above the proportionate size, while the peduncle appears relatively 

 small, the object being merely to bring sharply into view special fea- 

 tures rather than to give a final restoration. With regard to improba- 

 bility of expansion of the dome-forming disk see text. 



only that there were free-swimming antherozoids. For other- 

 wise the manner in which the decurved tips of the staminate 

 fronds lie appressed to the outer surface of the ovulate zone 

 and thus shut off the synangial region from it would have 

 tended to prevent direct pollination. Neither of these condi- 

 tions, as already explained in earlier papers, are probable, so 

 far as the species are known, the very immature condition of 

 the ovulate region as compared with synangial development 

 making it probable that in most cases the shedding of pollen 



