SPERMATOFHYTA 



331 



phloic siphonostele, shows a large pith, a thick or thin vascular cylinder, 

 and a small cortex. In contrast to the mesarch collateral bundles of the 

 Cycadofilicales, those of the Cordaitales were endarch and collateral. 

 Secondary wood was well developed, its tracheids having bordered pits in 



Fig. 280. Restoration of Dorycordaites, showing the roots, branching stem, simple leaves, 

 and clusters of strobili borne on lateral branches. The stem was actually much longer 

 than shown here. (After Grand' Eury.) 



several rows, as in the modern coniferous genus, Araucaria. The leaf 

 traces were double, collateral, and endarch, becoming mesarch in the 

 leaves. In most cases the venation of the leaves was dichotomous. 



Strobili. A feature of the Cordaitales was the presence of small strobili 

 of two kinds, both occurring on the same plant and borne in clusters on 

 lateral branches (Fig. 281). The strobili, about a centimeter in length, 

 were completely ensheathed by sterile bracts. The staminate strobili 

 were composed of spirally arranged microsporophylls and bracts, the lat- 



