42; 



others which were investigated, in that the leaves were some- 

 what less thick (about 210/i against about 280 /i from Green- 

 land and Scandinavia) and there were only two palisade-layers, 

 while those from Greenland and Scandinavia had three layers. 

 The leaves from the Faeroes, which have been investigated, 

 resembled those from Iceland. 



I? 



Fig. 55. ThaJictrum aJpinum. 



A, Transverse section of leaf (Godhavn; »Vi) B, Epidermis of the upper surface (Havne- 



!jord; 230/,); p pahsade-cells. C, Epidermis of the lower surface; (Godhavn; 230 1); ^he 



perforation of the wall has been drawn only in one cell. D, Surface section of spongy 



parenchyma (Godhavn; ^so/i). 



The leaf- s talk is obtusely square in transverse section. 

 The ring of sclerenchyma and the four large and four small 

 bundles resemble in structure the corresponding parts of the 

 stem. The epidermis contains chlorophyll and the cuticle is 

 slightly striped. The cortex consists of 4 — 6 layers. The pith 

 is large-celled and not broken down. 



