362 BOTANICAL GAZETTE [novembeb 



sporophylls in Cordaitales as probable, their continuation in Gink- 

 goales and Coniferales is quite possible, abortion of some of the 

 sporangia in the formation of mucilage or resin cavities, in such 

 forms as Ginkgo and Torreya, obscuring their true nature, but 

 showing the true peltate character when all of the sporangia develop, 

 as in Taxus. Worsdell, following the view put forward by 

 Celakovsky (2), considers the peltate sporophyll of Taxus to have 

 been derived from such a form as occurs in the Cordaitales, where 

 the pollen sacs are "erect and terminal on the radial sporophyll," 

 through such forms as found in Cephalolaxus and Torreya, where the 

 pollen sacs are "sub-terminal and pendulous, owing to a slight 

 prolongation of the axis of the sporophyll, between and beyond the 

 sacs, in a small protuberance," this condition being intermediate 

 between the Cordaitales situation and Taxus, "where the extended 

 terminal portion has become enlarged and flattened out into a very 

 distinct peltate structure." " Taxus thus represents an advance 

 from the earlier types of Cephalotaxus, Ginkgo, etc., toward the 

 subpeltate dorsiventral type of sporophyll of the true Coniferae." 

 One must question the necessity of such an explanation for either 

 the peltate sporophyll of the taxads or the dorsiventral one of most 

 conifers, in view of the historical occurrence of both of these types 

 in forms more primitive than even the Cordaitales. 



The significant features of the vascular anatomy of the strobilus 

 are the mesarch character of the terminal portion of the scale 

 bundles, as well as the appearance of centripetal xylem in the termi- 

 nal portion of the sporophyll bundle, where the bundle is not only 

 mesarch at times, but may also be exarch and concentric. This 

 indicates the very conservative nature of the staminate strobilus. 

 These primitive features, however, occur only in the terminal 

 portions of the strobilus, which may be regarded as an argument in 

 favor of the "advanced" character of Taxus, compared with forms 

 with more abundant centripetal xylem. 



Summary 



1. The staminate strobili occur in the axils of the leaves. The 

 buds can first be distinguished from other types of buds by the 

 broad apex. 



