164 O. Hagerup: Caprifoliaceae. 



year. The exodermis, with the remainder of the epidermis, 

 thus becomes the outermost layer ; its cell walls are slightly 

 thickened. Underneath is the starch carrying bark, which 

 occasionally exceeds several times in thickness the diameter 

 of the central cylinder. Towards the centre, the bark adjoins 

 an endodermis, the cells of which has thickened walls, those of 

 the passage cells excepted. During the fourth year the 

 whole of the bark is forced off, and the pericambium beco- 

 mes phellogen, which forms a cork, consisting of about 10 cell 

 layers (Giger). The central cylinder is diarch to pentarch, 

 and outermost is a distinctly bounded pericycle. Wood, 

 to fill the central cylinder, is quickly formed; its anatomic 

 structure is practically identical with that of the stem, and 

 shows distinctly annual rings. 



Summary. 



When compared with material from Denmark, Linnaea from 

 Greenland is distinguished by the following characteristics: 



The stem has shorter internodes, giving the plant a 

 more compact appearance. 



The leaves are smaller with slighter incisions, and the 

 perpendicular walls of the epidermis cells are thicker and 

 have more pronounced undulations. 



The mesophyll has smaller intercellular spaces and larger 

 palisade tissues. 



