172 



MORPHOLOGY OF GYMNOSPERMS 



of mycorhiza had been reported previously from the Coal-measures, 

 this observation is one of special interest. 



2. The spore-producing members 



THE STROBILI 



The small strobili, not often more than a centimeter in length, 

 are borne laterally upon short, simple or branched, lateral shoots 



(fig. 204). These strobilus- 

 bearing branches suggest in- 

 florescences; and although 

 \ — 'I'liliP^ ^p' % occurring among the leaves, 



they do not always seem to 

 be axillary. These structures 

 were recorded under the 

 general name Antholithus until 

 Grand 'Eury found Antho- 

 lithus in connection with the 

 leaf-bearing shoots of Cor- 

 daites. Since many of the 

 strobili cannot be referred with 

 certainty as yet to the definite 

 species of Cordaitales, the form 

 genus Cordaianthus has been 

 used to record most of them. 

 Our knowledge of the internal 

 structure of Cordaianthus has 

 come chiefly from the few sections made by Renault (3). Both 

 kinds of strobili are sheathed by bracts, so that it is not always 

 possible to distinguish them externally. 



THE MICROSPORANGIUM 



In Cordaianthus Penjonii (fig. 205) the staminate strobilus (i cm. 

 long) consists of a thick axis bearing spirally arranged bracts, among 

 which stamens are inserted. The stamens are either solitary or are 

 grouped near the apex of the axis. Each stamen consists of a more 

 or less elongated stalk bearing at its tip a cluster of three to six erect 

 sporangia (fig. 206). The wall of the sporangium is a single layer 



Fig. 204.- — Cordaites: portion of stem 

 showing one leaf and four branches, each 

 branch bearing numerous strobiH; Xf. — 

 After Grand 'Eury (2). 



