160 



O. Hagerup. 



Short- and long-shoots have in the main the same 

 anatomic structure. 



The Leaî. Its duration is from 2 to 3 years ; in shape it 

 varies somewhat, most often it is ovate, but elliptical-round 

 or nearly kidney-shaped leaves are also found. As a rule 

 2 faint incisions are to be seen on each side of the leaf, 

 but some variations are also found in this respect ; it is 



Fig. 3. The leaf. 



Epidermis: g. lower surface (material from Greenland) ; d, lower surface, o, upper surface., 

 with palisade cells added (material from Denmark). 



pinnately veined. Scattered hairs are present, of the same 

 type as those on the stem; on the lower surface of the 

 leaves are some glandular hairs, with a short one-celled 

 stalk and a many-celled head, which secretes a sticky sub- 

 stance in which fungus spores are often caught and germinate. 



The mesophyll shows that the leaf is a typical shade- 

 leaf, in conformity with its usual habitat (Fig. 4). 



The epidermis contains chorophyll ; the cells are largest 

 on the upper surface (Fig. 3). 



The perpendicular walls are undulating with thickened 

 outer ends (Fig. 4). This was especially pronounced on the 



