Further Notes on Floral Structures. 89 



branched cycad. To this species therefore the trunk should be 

 provisionally assigned. Although a rather young form, several 

 fruits are present, and an ovulate strobilus one centimeter in 

 diameter and about two in length has, in strong contrast to the 

 C. Marshiana strobili figured above, the same flatly convex 

 type of parenchymatous cushion as G. Wielandi. Whence it 

 follows that G. dacotensis with the allied C. superba, G. Marsh- 

 iana, and G nana, include a clear succession of forms passing 

 from the largest of compactly branched cycads to lesser and 

 finally small-sized and small-flowered, more freely branched 

 trunks. 



The floral indices of this series are therefore distinct ; 

 G. dacotensis having a larger disk of seventeen or more fronds 

 and 0. Marshiana a much smaller flower with eleven or twelve 

 fronds, while in G. nana the disk is unknown but the ovulate 

 cone varies from that of both the foregoing species in its con- 

 vex instead of elongate parenchymatous cushion. And as will 

 be illustrated in subsequent studies already fairly complete, 

 this same transition from the elongate primitive type of stro- 

 bilar axis to a convex or nearly flat parenchymatous cushion is 

 as strikingly illustrated by the strictly columnar species of the 

 Black Hawk localities. There too, an elongate axis is present 

 in the fruits of the great G. ingens and the tall G. Jenneyana, 

 while the fine columnar trunk G excelsa bears the largest cones 

 with the shortened or reduced axis or cushion type yet seen. 



# * * * •£ * ■& 



A few of the suggestions arising from the present study of 

 small cycad flowers in connection with the trunks that bear them 

 may well be given a tentative record here. 



Much stress has been laid in my American Fossil Cycads on 

 the process of branch formation with increased flower output, 

 in view of which Gycadeoidea Marshiana and G. nana have 

 much interest as now shown to typify the extreme of branch devel- 

 opment and floral reduction in the Gycadeoidece. But it is not 

 necessary to assume this family to be a direct derivative of 

 simple stemmed types ; its immediate ancestry may have had 

 freely branched forms with much slenderer stems. Even with- 

 out considering Gordaites it is obvious that free branching of 

 gymnosperms and reduction of floral organs are very ancient. 



It is then among the William sonian tribe that the search for 

 types of branch development and floral reduction must be con- 

 tinued. Nor can the role of the threefold process of branching, 

 sporophyll reduction, and acquisition of the angiospermous 

 emplacement in older cycad ophy tans have been a meaningless 

 one. This course of change must have been in evidence by 

 Permian time, while Wielandiella with wholly reduced sta- 



Am. Jour. Sci.— Fourth Series, Vol. XXXIII, No. 194.— February, 1912. 



7 



