13] 



VEGETATIONAL TYPES OF POLAR LANDS 



389 



hummocks, the microhabitat effect is extreme, the microhabitats 

 ranging from depressions occupied by dark boglets or puddles of 

 'free' water (seen in Fig. 113) to dry hillock tops occupied by 

 Lichens or, in favourably sheltered situations, xeromorphic ground- 

 shrubs. 



Tracts of ' grassy ' mesophytic tundra of any substantial extent 



Fig. 114. — Discontinuous tundra-like tract of mixed Grasses, Northern Wood- 

 rush {Luzula confusa agg.), forbs, and Polar Willow (Salix polaris agg.), in inland 

 valley, West Spitsbergen, grazed by a pair of wild Reindeer. Beyond is the dry 

 bouldery bed of a melt-water stream that is dry during most of the summer, and, 

 behind, barren scree and other slopes. 



are not common in the high- Arctic, though Fig. 114 shows a dis- 

 continuous but tundra-like patch of mixed Grasses, Northern Wood- 

 rush {Luzula confusa agg.), forbs, and Polar Willow {Salix polaris 

 agg.), that is sufficiently developed to attract Reindeer. It is situated 

 in a sheltered valley well inland in Spitsbergen, by the side of a 

 bouldery bed of a snow-water stream that is dry during most of 

 the summer. Still drier tvpes of tundra in these farthest north 

 lands tend to be dominated largely by Lichens and to be much 

 interrupted by rocks or bare patches — especially in exposed situations. 



