G. R. Wieland— Cycadeoidean Flower-hud Structure. 125 



Failing the deep incision now observed, the full significance of 

 that small notch was by no means at first appreciated, though 

 it could not escape observation when the drawings were made. 

 As reference to the figures shows, the groove was only seen near 

 its lower and shallower end at a height of a full centimeter or 

 more above the central cone. But fortunately, all the upper 

 portion of the bud before us is present, save a very small slen- 

 der tip, and the bracts are so broken away on one side as to 

 disclose the entire outline of the bract-enveloped disk apex, 

 which - as the drawing (fig. 4) shows rises in the form of an 

 absolutely symmetrical spired dome. 



With the trial section just described completed, it was possi- 

 ble to locate and cut to the best possible advantage the supple- 

 mentary longitudinal section. This as drawn in figure 4 in 

 conjunction with the view of the dome-shaped summit yields 

 nearly all further larger details of the floral structure and plan. 

 It brings to view the very heavy bracts, somewhat irregularly 

 appressed in position, the large peduncle and ovulate cone of 

 inverted pear-shape with a very minute and limited seed zone, 

 the exact thickness of the disk and its insertion, the decurved 

 microsporophyll tips, and finally the rather limited fertile or 

 synangia-bearing space, with the immense expansion of the 

 sterile rachidal region just at the base of the terminal dome. 

 Special features are the relative narrowness of the seed zone, 

 to the basal portion of which the microsporophyll tips exactly 

 reach as a complete enclosing curtain, and the high position of 

 the synangial region above the fertile zone of the seed. This 

 latter feature is partly paralleled in 0. Marshiana, but quite 

 different from the condition seen in C. dacotensis, where the 

 synangia grow far down in the campanula toward the base of 

 the ovulate strobilus. 



Comparison loith other Cycadeoidea Floioer Buds. 



This is indeed a flower of singular aspect. And it is safe to 

 say that the prolongation of its sterile spinose pairs of median 

 rachidal wings into a dome-like expansion, not only taking up 

 all the space between the outer husk of bracts but carrying 

 them up as a high summit, would never have been suspected 

 without actual observation. The long bush of terminal sterile 

 scales visible in nearly all ovulate cones not having the short 

 cushion easily led to the belief that the ovulate cone formed 

 a summit above the always decurved microsporophylls and 

 thus took up any unfilled space between the fertile organs and 

 the bracts rather than that any open tent-shaped space was left 

 between these organs and the floral envelope of hairy bracts. 

 The casts of Williamsonia gigas figured by Williamson seemed 

 to lend further support to such explanation of the outer form, 



