13] VEGETATIONAL TYPES OF POLAR LANDS 399 



in most of such exposed high-arctic tracts, with a large proportion 

 of the area typically occupied by barrens supporting little more than 

 occasional tufts of Arctic Poppy {Papaver radicatum s.l.) or Purple 

 Saxifrage {Saxifraga oppositifoUa agg.), although more mixed fell- 

 helds may occur in less unfavourable situations. On well-drained 

 banks there may be Grasses and some hardy but attractive forbs, 

 while very occasionally under the most favourable conditions a 

 limited tract of thin heath may be developed, though often one can 

 trek for days without encountering such a manifestation. The only 

 at all extensive tracts of closed vegetation are mostly of rather thin 

 marshy and often hummocky tundra (Fig. 113), and even here the 

 dominants rarely exceed a height of 30 cm. above the surface from 

 which they grow. Yet most of these vegetation-types and a fair 

 range of vascular plants are to be found right up to the highest 

 latitudes of land, between 83° and 84' N., in marked contrast to the 

 situation in Antarctica {see pp. 415 et seq.). 



Seaside and Other Local Types 



On sandy and fine-shingle maritime beaches in both low- and 

 middle-arctic belts there are usually scattered plants of Sea-purslane 

 {Arenaria peploides agg.) and Sea Lungwort {Mertensia maritima 

 agg.) on the foreshore and, farther up, stabilizing beds of Lyme- 

 grass {Elymiis arenarius s.l.) which may be fairly tall and luxuriant 

 (Fig. 124). In the high-arctic belt, Lyme-grass is unknown and 

 the other two are rare, so exposed sandy and shingly shores are 

 liable to be barren around high-tide mark. 



In sheltered and less well-drained seaside areas, muddy or sandy 

 ' salt-marshes ' are common though usually of very limited extent 

 in the Arctic. Even more than many other types of vegetation, 

 they show close similarity of form all around the southern portions 

 of the Arctic — and also, with natural depauperation, far northwards. 

 Thus in low-arctic areas they typically consist of a dwarfish grassy 

 sward dominated by Alkali-grasses (particularly the Creeping Alkali- 

 grass, PiiccineUia phryganodes agg.) and Sedges (particularly the Bear 

 Sedge, Carex uisina, and phases of the Salt-marsh Sedge, C. salina 

 s.l.), with associated Low Chickweed {Stellaria humifusa), Scurvy- 

 grass {Cochleaiia officinalis s.l.). Pacific Silverweed (PotentiUa egedii 

 agg.), and other halophytes. Fig. 125 shows such a sah-marsh 

 on the south coast of Baffin Island. Except for the usual absence 

 farther north of the Silverweed and the substitution of Salt-marsh 



