Cornaceæ. 



143 



consists of composite granules. On the innerside an even 

 transition from the bark-cells to the phloem is to be found. 

 As in the stem, the wood consists of a coherent ring, and 

 has rather indistinct annual rings. The secondary wood 

 consists of trabecular and ringpored vessels, together with 

 tracheids and wood-parenchyma, this latter being rich 



Fig. 8. Cornus suecica. 

 Transverse section, showing secondary' structure of root; S, cork (Greenland); about sl2 /i- 



in starch. Medullary rays are not present, the medulla con- 

 sisting of large cells filled with starch. 



The bark-cells of the rhizome contain large quantities 

 of tannin, which is also found in the bark-cells of the stem 

 and in the leaf. 



The Root: the primary structure is diarch, it has a 

 suberized rather thickwalled endodermis and a distinct 

 pericycle (Fig. 7). 



