394 



web of branches and roots lying several cm above the worn- 

 olT soil. 



The plants stand, as a rule, singly, but the bigger ligneous 

 plants, such a Dnjas and Salix yet give shelter and lee to the 

 smaller, which, for this same reason, accompany them; thus 

 Chamaenerium and Cerastium are hardly cvlt seen except 



Fig. 17. Lesquerella nrctica on stoin plaiii. Tlic lluweiinu :liuul: eiecl; 

 those fructifying decumbent. Klitdalen. (From photo, by Chr. Kruuse). 



sheltered by the willows. Yet it need not be but a small 

 stone, arising only a few cm above the ground, which con- 

 stitutes the condition of growth for an individual; indeed, I saw 

 in one place Arenaria ciliata making shelter for Potentilla 

 nivea (fig. 18). 



In lee of each plant-tuft a small sand drift has gathered; 

 It need not be more than 1 — 2 cm thick, but may very well 

 be 15 cm in breadth and 40 cm long (the numbers corres- 



