264 STRUCTURAL BOTANY 



The whole of the cortex, as well as the piliferous 

 layer, has to be bored through by the rootlet before 

 it reaches the exterior. It completely absorbs all 

 the tissues which lie in its way. 



The only peculiarities in the mode of origin of the 

 branches of the root, in this instance, depend on the 

 fact that the pericycle is of unusual thickness, and 

 are not characteristic of the class generally, but only 

 of the Fir and its nearer allies. In all the essential 

 points the mode of branching of the root is identical 

 in Gymnosperms and in Dicotyledons. 



SUMMARY OF THE VEGETATIVE STRUCTURE OF CONIFERS 



In the general morphology and anatomy of both 

 stem and root the Conifers agree closely with 

 Dicotyledons, while they bear little or no resem- 

 blance to the Monocotyledons. The distribution and 

 longitudinal course of the vascular bundles and the 

 mode of secondary growth are practically identical 

 in Conifers and Dicotyledons. Yet in other respects 

 we find very great differences. This is especially the 

 case as regards the leaves. 



Some Conifers have leaves of more complex struc- 

 ture than those of the Fir, but still it is characteristic 

 of the order to have a comparatively simple bundle- 

 system in the leaf. Its simplicity is constantly com- 

 pensated for by the formation of transfusion tissue 

 and albuminous cells outside the actual bundles. 



In the more minute structure there are also 

 important differences ; the entire absence of vessels 

 from the wood is a striking character. 



