46 



Knud Jessen. 



exhibited by the majority of the land-species of Ranunculus, 

 while a further development in the direction indicated in 

 Fig. 18, A would lead to a leaf of the R. glacialis type 1 . 



The diameter of the flower varies greatly; Wolf records 



Fig. 18. Potentilla. maculata. 



A, Transverse section of leaf. B, Transverse section of leaf. C, Cortical 

 cell with mucilaginous inner wall from the lower surface of the leaf. D, 

 Stalked gland from the upper leaf-surface. E, Epidermis of the upper leaf- 

 surface. F, Epidermis of the lower leaf-surface. G, Section of the outer- 

 most layer of the spongy parenchyma. A and G are of leaves from Spitz- 

 bergen, the others are of leaves from Greenland (A, H C, D, E and G 

 about 175 /i; E, about ""/O- 



from 10 to 25 mm. I measured flowers from Greenland 

 which were about 15 mm. in diameter. The petals are usually 

 golden yellow in colour, sometimes they are of one colour, 

 sometimes there is a saffron coloured spot at the base (Wolf). 



1 Ranunculaceæ by Knud Jessen: Arctic Flow. PL I. 6. Meddel, 

 om Grönland, Bd. 36. 



